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[PLUG POWER LOGO]

[H POWER LOGO]

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1.

To consider and vote on a proposal to approve the issuance of shares of common stock of Plug Power Inc. pursuant to the Agreement and Plan of Merger, dated as of November 11, 2002, by and among Plug Power Inc., a Delaware corporation, Monmouth Acquisition Corp., a Delaware corporation and a wholly-owned subsidiary of Plug Power Inc., and H Power Corp., a Delaware corporation, as amended, a copy of which is attached as Annex A to the accompanying joint proxy statement/prospectus.

2.

To consider and vote on a proposal to exchange options to purchase shares of common stock of Plug Power Inc. held by its employees for shares of restricted common stock of Plug Power Inc., in accordance with the terms and conditions described in the accompanying joint proxy statement/prospectus.

3.

To transact any other business as may properly come before the special meeting and any adjournments or postponements of the special meeting.

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1.

To consider and vote on a proposal to adopt and approve the Agreement and Plan of Merger, dated as of November 11, 2002, by and among Plug Power Inc., a Delaware corporation, Monmouth Acquisition Corp., a Delaware corporation and a wholly-owned subsidiary of Plug Power, and H Power Corp., a Delaware corporation, as amended, a copy of which is attached as Annex A to the accompanying joint proxy statement/prospectus, and to approve the merger as contemplated by the merger agreement.

2.

To transact any other business that may properly come before the special meeting and any adjournment or postponement of the special meeting.

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Q:

Why are Plug Power and H Power proposing the merger? (See pages 59 and 72)

A:

Plug Power and H Power are proposing the merger because they believe the resulting combined company will be a stronger, better capitalized and more competitive company. Plug Power and H Power believe that the merger will provide significant potential benefits and resources, including:

•

cash resources to fund the combined company’s growth and development;

•

benefits created from the complementary resources of Plug Power and H Power, including complementary financial, technology and intellectual property resources; and

•

potential synergy benefits from cost savings and integration of the companies’ strategic partners and suppliers.

Overall,

both Plug Power and H Power believe that the merger will provide added value to their respective stockholders. Achieving these anticipated benefits, however, is subject to certain risks discussed in the section entitled “Risk Factors” beginning on page 27.

Q:

What will I receive in the merger? (See  page 79)

A:

H Power Stockholders:

If the merger is completed, Plug Power and H Power estimate that each H Power stockholder will receive approximately .89 shares of Plug Power common stock for each share of H Power common stock. This amount is an estimate based on (1) 10,776,548 shares of H Power common stock outstanding as of the date of this joint proxy statement/prospectus; (2) an estimated transaction value price of $50,675,000 based on the estimated value of H Power’s net cash of $36,675,000 (as defined in the merger agreement) as of the date of this joint proxy statement/prospectus and (3) an estimated average trading price of $5.29 per share of Plug Power common stock (based on the closing price of $5.05 per share of Plug Power common stock on the last business day prior to the date of this joint proxy statement/prospectus and adjusted to $5.29 per share for the collar). The actual number of shares of Plug Power common stock that each H Power stockholder will receive for each share of H Power common stock may be different than .89, however, as the exchange ratio for H Power common stock is determined based in part on:

•

the number of shares of H Power common stock outstanding immediately prior to the effective time of the merger;

•

the average trading price for shares of Plug Power common stock for 10 randomly selected days in the 20 trading day period ending on the second trading day prior to the effective time of the merger; and

•

the transaction value price, which is determined based on the value of H Power’s net cash (as defined in the merger agreement) at the effective time of the merger.

For example, if H Power’s net cash (as defined in the merger agreement) is equal to $36,675,000 then the number of shares of Plug Power common stock that each H Power stockholder will receive for each share of H Power common stock will, depending on the number of shares of H Power common stock outstanding immediately prior to the effective time of the merger and the average Plug Power common stock price, range between .73 and .89. Additionally, as a further illustration of the impact on the exchange ratio, if H Power’s net cash is equal to an amount between $34,675,000 and $38,675,000, then the number of shares of Plug Power common stock that each H Power stockholder will receive for each share of H Power common stock will, depending on the number of shares of H Power common stock outstanding immediately prior to the effective time of the merger and the average Plug Power common stock price, range between .70 and .92. Each H Power stockholder will also receive cash, without interest, rather than a fractional

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share of Plug Power common stock that he, she or it would otherwise be entitled to receive in the merger.

For a description of how the exchange ratio will be determined, and examples of the exchange ratio based on assumptions regarding H Power’s net cash and the average Plug Power common stock price, each at the effective time of the merger, see the section of this joint proxy statement/prospectus titled “The Merger and Related Transactions—The Merger Agreement—Conversion of H Power Common Stock in the Merger.” Prior to each company’s respective special meeting of stockholders, the current estimated exchange ratio will be posted on Plug Power’s website at www.plugpower.com and on H Power’s website at www.hpower.com.

Q:

Will H Power stockholders be able to trade the Plug Power common stock that they receive in the merger? (See page 104)

A:

Yes. The Plug Power common stock issued in the merger will be registered with the Securities and Exchange Commission and listed on the Nasdaq National Market under the symbol “PLUG.” All shares of Plug Power common stock that you receive in the merger will be freely transferable unless you are deemed to be an affiliate of H Power prior to the completion of the merger or an affiliate of Plug Power after the completion of the merger, or your shares are subject to other contractual restrictions. Shares of Plug Power common stock received by persons deemed to be affiliates in the merger may only be sold in compliance with Rule 145 under the Securities Act or as otherwise permitted under the Securities Act.

Q:

When do Plug Power and H Power expect to complete the merger?

A:

Plug Power and H Power expect to complete the merger when all of the conditions to completion of the merger contained in the merger agreement have been satisfied or waived. The stockholders of H Power must approve the merger agreement and the merger at their special stockholders meeting and the stockholders of Plug Power must approve the issuance of shares of Plug Power common stock pursuant to the merger agreement at their special stockholders meeting.

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Q:

What happens if the merger is not completed? (See page 96)

A:

If the merger is not completed, each of Plug Power and H Power will continue as independent companies. In addition, under the terms of the merger agreement, H Power may be required to pay Plug Power a termination fee of $2,000,000. Also, each party may be required to reimburse the other for out-of-pocket expenses, including legal, accounting, investment banking, printing and other fees, related to this transaction if the merger is not completed. For a more complete discussion of requirements relating to payments of fees and expenses by each of Plug Power and H Power see the section entitled “The Merger and Related Transactions—The Merger Agreement—Payment of Termination Fee and Expenses” in this joint proxy statement/prospectus.

Q:

What vote is required to approve the merger? (See page 49)

A:

Approval of the merger agreement and the transactions contemplated by the merger agreement requires the affirmative vote of the holders of a majority of the outstanding shares of H Power common stock as of the record date. Although the approval of the stockholders of Plug Power is not required to effect the merger pursuant to Delaware general corporation law, Plug Power’s organizational documents or any other regulatory or listing requirements applicable to Plug Power, the board of directors of Plug Power has determined that the issuance of shares of Plug Power common stock pursuant to the merger agreement will be subject to, and the merger agreement requires, the affirmative vote of the holders of a majority of the shares of Plug Power common stock present in person or represented by proxy at the special meeting of Plug Power stockholders on such matter. In addition, approval of the stock option exchange is subject to the same voting requirement as the merger.

Q:

How do I vote on the merger? (See pages 48 and 51)

A:

First, please review the information contained or incorporated by reference in this joint proxy statement/prospectus, including the annexes, as it contains important information about Plug Power, H Power and the merger. It also contains important information about what each of the boards of directors of Plug Power and H Power, respectively, considered in evaluating the merger. Next, complete and sign the enclosed proxy card, and then mail it in the enclosed return envelope as soon as possible so that your shares can be voted at your company’s special meeting of stockholders at which, in the case of H Power, the merger agreement and the merger will be presented and voted upon, or, in the case of Plug Power, the issuance of shares of Plug Power common stock pursuant to the merger agreement and the approval of the stock option exchange will be presented and voted upon. You may also attend the special meeting of your company in person and vote at the special meeting instead of submitting a proxy.

Q:

What happens if I don’t indicate how to vote my proxy? (See pages 47 and 50)

A:

If you sign and send in your proxy, but do not include instructions on how to vote your properly signed proxy card, your shares will be voted FOR adoption and approval of the merger agreement and approval of the merger if you are an H Power stockholder or FOR the issuance of shares of Plug Power common stock pursuant to the merger agreement and FOR the stock option exchange if you are a Plug Power stockholder.

Q:

What happens if I don’t return a proxy card? (See pages 47 and 50)

A:

If you are a stockholder of H Power, not returning your proxy card will have the same effect as

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voting against adoption and approval of the merger agreement and against approval of the merger. If you are a stockholder of Plug Power, not returning your proxy card will have no effect as to the approval of the proposal to issue shares of Plug Power common stock pursuant to the merger agreement or the proposal to approve the stock option exchange.

Q:

Can I change my vote after I have mailed my signed proxy card? (See pages 48 and 51)

A:

Yes. You can change your vote at any time before your proxy is voted at the special meeting of your company’s stockholders at which, in the case of H Power, the merger agreement and the merger will be presented and voted upon, and in the case of Plug Power, the issuance of shares of Plug Power common stock pursuant to the merger agreement and the proposal to approve the stock option exchange will be presented and voted upon. You can do this in one of three ways:

•

first, you can send a written notice stating that you would like to revoke your proxy to the appropriate address below;

•

second, you can complete and submit a later-dated proxy card to the appropriate address below; or

•

third, you can attend the special meeting of Plug Power or H Power, as appropriate, and vote in person. Your attendance at the special meeting alone will not revoke your proxy. You must vote at the special meeting in order to revoke your previously submitted proxy.

Q:

Can I submit my proxy by telephone or over the Internet?

A:

If you hold shares directly, then you may not vote by telephone or over the Internet. If you hold your shares through a bank or brokerage firm, you may be able to submit your proxy by telephone or over the Internet. You should refer to the proxy card provided by your bank or brokerage firm for instructions about how to vote. If you vote by telephone or over the Internet, you do not need to complete and mail your proxy card.

Q:

If my broker holds my shares in “street name,” will my broker vote my shares for me? (See pages 48 and 51)

A:

No. Your broker will not be able to vote your shares without instructions from you. If you do not provide your broker with voting instructions, your shares may be considered present at the special meeting for purposes of determining a quorum, but will not be considered to have been voted in favor of adoption and approval of the merger agreement or approval of the merger, in the case of H Power stockholders, or in favor of approval of the issuance of shares of Plug Power common stock pursuant to the merger agreement or approval of the stock option exchange, in the case of Plug Power stockholders. As a result, failure to provide your broker with voting instructions will have the effect of a vote against the merger agreement and against the approval of the merger if you are a stockholder of H Power, or the effect of a vote against approval of the issuance of shares of Plug Power common stock pursuant to the merger agreement and against the stock option exchange if you are stockholder of Plug Power. If you have instructed a broker to vote your shares and wish to change your vote, you must follow the directions received from your broker to change those instructions.

Q:

Should I send my H Power stock certificates now? (See page 83)

A:

No. If the merger is completed, Plug Power will send you written instructions for exchanging your H Power stock certificates for Plug Power

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stock certificates. In the meantime, you should retain your certificates as the H Power stock certificates are still valid. Please do not send in your stock certificates with your proxy. If you send your stock certificates to Plug Power, Plug Power assumes no risk of loss.

Q:

Am I entitled to appraisal rights in connection with the merger? (See page 104)

A:

No. Appraisal rights are not available under applicable law in connection with the merger.

Q:

Are there any risks I should consider in deciding whether to vote for the merger or the issuance of shares of Plug Power common stock in connection with the merger?

A:

Yes. In the section entitled “Risk Factors” beginning on page 27 of this joint proxy statement/prospectus, Plug Power and H Power have described a number of risk factors that you should consider.

Q:

What are the tax consequences to me of the merger? (See page 100)

A:

Plug Power and H Power intend to treat the merger in such a manner that receipt of Plug Power common stock in the merger would be tax-free to H Power’s stockholders. However, in the opinion of counsel, it is unclear whether the merger will qualify as a tax-free reorganization, and thus it is possible that the H Power stockholders will be required to recognize gain or loss for U.S. federal income tax purposes in connection with the merger. We urge you to consider carefully the discussion of the tax consequences related to the merger and to review these tax consequences with your tax advisor.

Q:

Who can help answer my questions about the proposals?

A:

If you have any questions about the proposals presented in this joint proxy statement/prospectus, you should contact:

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increased visibility and market capitalization of the combined entity;

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increased financial strength of the combined entity;

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greater intellectual property and technical resources of the combined entity;

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the fact that on November 10, 2002, the date the merger agreement was approved, the proposed exchange ratio offered a significant premium of 106% to H Power stockholders relative to H Power’s closing stock price on the previous trading day;

•

the risks of remaining an independent entity, and the lack of definitiveness of any financing proposal; and

•

the opinion of Lehman Brothers that, as of the date of such opinion and based upon and subject to the assumptions, limitations and qualifications set forth therein, the exchange ratio offered to the holders of  H Power common stock in the merger was fair from a financial point of view to such holders.

•

risks associated with fluctuations in Plug Power’s stock price prior to the merger;

•

the risk of disruption of sales momentum and H Power’s operations as a result of uncertainties created by the announcement of the merger;

•

the risk that certain conditions in the merger agreement may have the effect of discouraging alternative proposals for a business combination with another third party;

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•

the interests of the directors and officers that are different from, or in addition to, those of H Power’s stockholders generally, including the receipt of change of control payments under the employment agreements with certain executive officers of H Power; and

•

other applicable risks described in the section of this joint proxy statement/prospectus entitled “Risk Factors” on page 27.

•

the opinion of Stephens Inc., Plug Power’s financial advisor, to the effect that as of November 11, 2002, the exchange ratio set forth in the merger agreement was fair, from a financial point of view, to Plug Power;

•

H Power’s cash reserves and Plug Power’s belief that the addition of such cash reserves to its own balance sheet would provide Plug Power with sufficient cash to help fund operations;

•

H Power’s intellectual property, technical resources and other assets;

•

the opportunity to enhance stockholder value by combining two complementary businesses;

•

the belief that the merger represents the most favorable alternative currently available to Plug Power to increase its capital resources and further its financing and business objectives;

•

the belief that the combined company will be in a better position to continue to compete effectively in the fuel cell industry;

•

the terms of the merger agreement, including Plug Power’s right to receive a $2,000,000 termination fee or to be reimbursed for its expenses in the event that it terminates the merger agreement under certain circumstances; and

•

potential synergy benefits, including cost savings and access to H Power’s partners and suppliers.

•

the risk that the potential benefits of the merger may not be realized, in part or at all;

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•

the risk that the merger may not be consummated;

•

the risk of management and employee disruption associated with the merger;

•

the potential costs the combined company may incur to (1) terminate, renegotiate or amend H Power’s existing obligations, including real estate and facility leases, (2) streamline the combined company’s business, (3) reduce excess capacity, including terminating employees and (4) eliminate redundant operations, including the consolidation of H Power’s operations into Plug Power’s headquarters in Latham, New York.

•

the dilutive effects of the merger upon existing Plug Power stockholders;

•

the risk that the merger could adversely affect Plug Power’s stock price or Plug Power’s relationship with some of its existing or potential customers, suppliers or strategic partners;

•

the significant costs involved in consummating the merger; and

•

other applicable risks described in the section of this joint proxy statement/prospectus entitled “Risk Factors” on page 27.

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•

Dr. H. Frank Gibbard, chief executive officer of H Power, is a party to a Second Amended and Restated Employment Agreement, dated as of August 1, 2002, which provides that, among other things, (1) Dr. Gibbard must devote substantially all of his business time, ability and attention to H Power’s business and affairs and he receives an annual base salary of $240,000, (2) if Dr. Gibbard is terminated for reasons other than for cause, he may be entitled to receive benefits and payments of his salary through the end of his employment term and (3) if, within a year after a change in control, H Power terminates Dr. Gibbard or assigns him duties materially inconsistent with his position, he may be entitled to receive a lump sum payment equal to two times his then annual base salary and incentive compensation, currently aggregating approximately $480,000.

•

Mr. William Zang, chief financial officer of H Power, is a party to an amended Officer’s Employment Agreement, effective as of August 1, 2002, which provides that, among other things, (1) Mr. Zang must devote substantially all of his business time, ability and attention to H Power’s business and affairs and he receives an annual base salary of $190,000, (2) if Mr. Zang is terminated for reasons other than for cause, he may be entitled to receive benefits and payments of his salary through the end of his employment term and (3) if, within a year after a change in control, H Power terminates Mr. Zang or assigns him duties materially inconsistent with his position, he may be entitled to receive a lump sum payment equal to one and one-half times his then annual base salary and incentive compensation, currently aggregating approximately $292,000.

•

Mr. Dudley Wass, chief operating officer of H Power, is a party to an amended Officer’s Employment Agreement, effective as of August 1, 2002, which provides that, among other things, (1) Mr. Wass must devote substantially all of his business time, ability and attention to H Power’s business and affairs and receives an annual base salary of $215,000, (2) if Mr. Wass is terminated for reasons other than for cause, he may be entitled to receive benefits and payments of his salary through the end of his employment term and (3) if, within a year after a change in control, H Power terminates Mr. Wass or assigns him duties materially inconsistent with his position, he may be entitled to receive a lump sum payment equal to one and one-half times his then annual base salary and incentive compensation, currently aggregating $315,000.

•

Mr. Paul McNeill, vice president of business development, marketing and sales of H Power, is a party to an amended Officer’s Employment Agreement, effective as of August 1, 2002, which provides that, among other things, (1) Mr. McNeill must devote substantially all of his business time, ability and attention to H Power’s business and affairs and he receives an annual base salary of $135,000, (2) if Mr. McNeill is terminated for reasons other than for cause, he may be entitled to receive benefits and payments of his salary through the end of his employment term and (3) if, within a year after change in control, H Power terminates Mr. McNeill or assigns him duties materially inconsistent with his position, he may be entitled to receive a lump sum payment equal to one and one-half times his then annual base salary and incentive compensation, currently aggregating $195,000.

•

In addition, Messrs. Zang and Wass are entitled to receive incentive bonuses of $150,000 and $50,000, respectively, relating to incentives to reduce H Power’s cash burn rate in order to maintain stockholder value.

•

The vesting on 1,500 outstanding options held by each of 5 non-employee directors of H Power to purchase H Power common stock will accelerate immediately prior to the merger.

•

Lehman Brothers, which H Power has retained as an investment banker with respect to the merger, will receive a fee of $1.5 million in addition to reimbursement of reasonable expenses upon the closing of the merger transaction, net of monthly retainer fees received prior to the closing of the merger. Mr. Clark, a member of H Power’s board of directors, is currently a vice-chairman of Lehman Brothers.

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*

For the period June 27, 1997 (date of inception) to December 31, 1997

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(1)

Includes non-cash stock compensation expense of $4,400, $5,175 and $711 in the years ended May 31, 2001, 2000 and 1999, respectively.

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(1)

The estimated exchange ratio is .89 shares of Plug Power common stock for each share of H Power common stock based on (i) 10,776,548 shares of H Power common stock outstanding on the date of this joint proxy statement/prospectus, (ii) an average share price of $5.29 per share of Plug Power common stock (based on the closing price of $5.05 per share of Plug Power common stock on the last business day prior to the date of this joint proxy statement/prospectus and adjusted to $5.29 per share as a result of the collar) and (iii) an estimated net cash value of $36,675,000. This estimated exchange ratio has been used to present the pro forma information based on the latest information available. The actual exchange ratio for H Power common stock in the merger may be different than the estimated exchange ratio. The exchange ratio could range from .73 to .89, exclusive of any adjustment required based upon H Power’s actual net cash at the effective time of the merger, as defined in the merger agreement. If the exchange ratio is .73 shares of Plug Power common stock for each share of H Power common stock, the number of shares of Plug Power common stock issued in connection with the merger would decrease to approximately 7.8 million shares from approximately 9.6 million shares and the pro forma loss per share, basic and diluted, for the twelve month period ended December 31, 2001 would be $(1.86) based on the weighted average number of shares outstanding, basic and diluted, of 54,672,394. If the exchange ratio is .73 shares of Plug Power common stock for each share of H Power common stock, the pro forma loss per share, basic and diluted, for the nine month period ended September 30, 2002 would be $(0.92) based on the weighted average number of shares outstanding, basic and diluted, of 58,390,441. Any change to the actual net cash at the effective time of the merger will affect the final transaction value and the exchange ratio as determined pursuant to the formula within the merger agreement. An additional summary of the effect of changes in net cash and the average Plug Power common stock price, both as determined pursuant to the merger agreement, is presented within note 3 on page 115 to further illustrate the impact to the relevant pro forma financial information. For further information concerning the estimated exchange ratio and the factors that may cause it to be adjusted, see the section of this document titled “The Merger and Related Transactions—The Merger Agreement—Collar Adjustment and Net Cash Adjustment.”

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(1)

The estimated exchange ratio is .89 shares of Plug Power common stock for each share of H Power common stock based on (i) 10,776,548 shares of H Power common stock outstanding on the date of this joint proxy statement/prospectus, (ii) an average share price of $5.29 per share of Plug Power common stock (based on the closing price of $5.05 per share of Plug Power common stock on the last business day prior to the date of this joint proxy statement/prospectus and adjusted to $5.29 per share as a result of the collar) and (iii) an estimated net cash value of $36,675,000. This exchange ratio has been used to present the pro forma information based on the latest information available and may be subject to change on completion of the transaction. The exchange ratio could range from .73 to .89, exclusive of any adjustment required based upon H Power’s actual net cash at the effective time of the merger, as defined in the merger agreement. If the exchange ratio is .73 shares of Plug Power common stock for each share of H Power common stock, the loss per share, basic and diluted, for pro forma combined would be $(1.86) based on the weighted average number of shares outstanding, basic and diluted, of 54,672,394. The actual exchange ratio for H Power

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common stock in the merger may be different than the assumed exchange ratio. Any change to the actual net cash at the effective time of the merger will affect the final transaction value and exchange ratio as determined pursuant to the formula within the merger agreement. An additional summary of the effect of changes in net cash and the average Plug Power common stock price, both as determined pursuant to the merger agreement, is presented within note 3 on page 115 to further illustrate the impact to the relevant pro forma financial information. For further information concerning the estimated exchange ratio and factors that may cause it to be adjusted, see the section of this joint proxy statement/prospectus entitled “The Merger and Related Transactions—The Merger Agreement—Collar Adjustment and Net Cash Adjustment” on page 82.

(2)

The estimated exchange ratio is .89 shares of Plug Power common stock for each share of H Power common stock based on (i) 10,776,548 shares of H Power common stock outstanding on the date of this joint proxy statement/prospectus, (ii) an average share price of $5.29 per share of Plug Power common stock (based on the closing price of $5.05 per share of Plug Power common stock on the last business day prior to the date of this joint proxy statement/prospectus and adjusted to $5.29 per share as a result of the collar) and (iii) a net cash value of $36,675,000. This exchange ratio has been used to present the pro forma information based on the information available and may be subject to change on completion of the transaction. The exchange ratio could range from .73 to .89, exclusive of any adjustment required based upon H Power’s actual net cash at the effective time of the merger, as defined in the merger agreement. If the exchange ratio is .73 shares of Plug Power common stock for each share of H Power common stock, the loss per share, basic and diluted, for pro forma combined would be $(0.92) based on the weighted average number of shares outstanding, basic and diluted, of 58,390,441. The actual exchange ratio for H Power common stock in the merger may be different than the assumed exchanged ratio. Any change to the actual net cash at the effective time of the merger will affect the final transaction value and exchange ratio as determined pursuant to the formula within the merger agreement. An additional summary of the effect of changes in net cash and the average Plug Power common stock price, both as determined pursuant to the merger agreement, is presented within note 3 on page 115 to further illustrate the impact to the relevant pro forma financial information. For further information concerning the estimated exchange ratio and the factors that may cause it to be adjusted, see the section of this joint proxy statement/prospectus entitled “The Merger and Related Transactions—The Merger Agreement—Collar Adjustment and Net Cash Adjustment” on page 82.

(3)

The unaudited equivalent pro forma per share amounts are calculated by multiplying the unaudited combined pro forma per share amounts by an assumed exchange ratio of .89 of a share of Plug Power common stock for each outstanding share of H Power common stock. The estimated exchange ratio of .89 shares of Plug Power common stock for each share of H Power common stock is based on 10,776,548 shares of H Power common stock outstanding, an average share price of $5.29 per share of Plug Power common stock and an estimated net cash value of $36,675,000. This exchange ratio has been used to present the pro forma financial information based on the latest information available and may be subject to change on completion of the transaction.

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*

Commencing on August 9, 2000 for H Power.

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•

the satisfaction of the conditions to closing, including receipt of stockholder and regulatory approvals;

•

the expected closing date of the merger;

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the risk that the merger will not close;

•

the risk that the merger will not be treated as a tax-free reorganization for United States federal income tax purposes;

•

the risk that Plug Power will not integrate and restructure the acquired business successfully;

•

the risk that Plug Power will incur unanticipated costs to integrate and restructure the acquired business;

•

the risk that H Power will require more cash than anticipated prior to closing;

•

fluctuations in the trading price and volume of Plug Power’s common stock;

•

the risk that continuity of H Power’s operations will be disrupted in the event the transaction does not close;

•

Plug Power’s ability to develop a commercially viable fuel cell system;

•

the cost and time required for Plug Power to develop fuel cell systems;

•

market acceptance of Plug Power’s fuel cell systems;

•

Plug Power’s reliance on its relationship with certain affiliates of General Electric;

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•

Plug Power’s ability to perform on its multi-generation product plan in a manner satisfactory to its distribution partners;

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Plug Power’s ability to manufacture fuel cell systems on a commercial basis;

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competitive factors, such as price competition, competition from other power technologies and competition from other fuel cell companies and the cost and availability of components and parts for Plug Power’s fuel cell systems;

•

the ability to raise and provide the necessary capital to develop, manufacture and market Plug Power’s fuel cell systems;

•

Plug Power’s ability to lower the cost of its fuel cell systems and demonstrate their reliability; and

•

the cost of complying with current and future governmental regulations.

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•

H Power may be required, under certain circumstances, to pay to Plug Power a termination fee of $2,000,000;

•

either Plug Power or H Power may be required, under certain circumstances, to pay to the other party particular out-of-pocket expenses incurred in connection with pursuing the merger;

•

both companies may experience a negative reaction, from both the financial markets and customers, suppliers or partners of each company, to the termination of the merger;

•

each company must pay its own costs related to the merger (subject to reimbursement by the other party in particular cases), such as amounts payable to legal and financial advisors and independent accountants, even if the merger is not completed;

•

the price of Plug Power’s and/or H Power’s common stock may decline as a result of the costs associated with the merger and/or to the extent that the current market price of Plug Power’s and/or H Power’s common stock reflects a market assumption that the merger will be completed;

•

either company may forego other opportunities which would otherwise be available had the merger agreement not been executed, including, without limitation, foregone opportunities as a result of certain affirmative and negative covenants made by H Power in the merger agreement, such as covenants affecting the conduct of its business outside the ordinary course of business; and

•

either company may be unable to obtain additional sources of financing or conclude another sale or merger transaction on favorable terms, or at all, and the board of directors of either company may determine that the best alternative is to discontinue certain operations, liquidate certain assets, reduce expenditures, and take other actions required to limit operations in a manner inconsistent with current development and commercialization plans.

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•

the diversion of management’s attention from other ongoing business concerns;

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the inability to utilize the acquired resources effectively; and

•

demonstrating to the combined company’s customers, suppliers and partners that the merger will not result in adverse changes in client service standards or business focus.

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•

the integration of Plug Power and H Power is unsuccessful;

•

Plug Power does not achieve the perceived benefits of the merger as rapidly or to the extent anticipated by financial or industry analysts or investors; or

•

the effect of the merger on Plug Power’s financial results or condition is not consistent with the expectations of financial or industry analysts or investors.

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•

the accelerated vesting of certain stock options held by certain non-employee directors of H Power as a result of the merger;

•

the receipt of severance payments by certain executive officers in the event that such individuals resign or terminate their employment with H Power subsequent to the signing of the merger agreement;

•

the receipt of payments, pursuant to a termination agreement by Energy Co-Opportunity, Inc. and ECO Fuel Cells, LLC, which has a representative on the H Power board of directors;

•

the engagement of Lehman Brothers, a vice-chairman of which is a director of H Power’s board of directors, as H Power’s financial advisor in connection with the merger; and

•

the receipt of ongoing indemnification and insurance coverage with respect to acts taken and omissions to take action in their capacities as directors and officers of H Power prior to the effective time of the merger.

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(1)

the sum of the market value of Plug Power common stock issued in connection with the merger;

(2)

the fair value of H Power stock options assumed by Plug Power; and

(3)

the amount of direct transaction costs incurred by Plug Power.

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•

the cost competitiveness of fuel cell systems,

•

the future costs of natural gas, propane and other fuels expected to be used by our systems,

•

consumer reluctance to try a new product,

•

consumer perceptions of Plug Power’s systems’ safety,

•

regulatory requirements, and

•

the emergence of newer, more competitive technologies and products.

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the termination of employment arrangements with certain employees;

•

reductions in expenditures for research and development;

•

the closing of the New Jersey facilities; and

•

the termination of certain customer contracts.

•

the inability to retain employees or hire new employees with similar qualifications on a timely basis;

•

With regard to the closing of certain facilities, the inability of H Power to successfully transfer its fuel cell stack technology from the facility being closed to another facility;

•

delays in further development of H Power’s residential fuel cell systems due to reductions in spending relating to research and development; and

•

delays in the timely production of its fuel cell products due to the suspension of field testing pursuant to certain customer contracts.

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1.

to consider and vote upon a proposal to approve the issuance of shares of common stock of Plug Power pursuant to the merger agreement;

2.

to consider and vote upon a proposal to exchange options to purchase shares of common stock of Plug Power held by its employees for shares of restricted common stock of Plug Power, in accordance with the terms and conditions described in this joint proxy statement/prospectus; and

3.

to transact any other business that may properly come before the special meeting and any adjournment or postponement of the special meeting.

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•

delivering to the Secretary of Plug Power a later-dated signed notice of revocation;

•

delivering to the Secretary of Plug Power a later-dated, signed proxy (which will automatically replace any earlier dated proxy card that you returned); or

•

attending the special meeting and voting in person.

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1.

to consider and vote upon a proposal to adopt and approve the merger agreement and approve the merger; and

2.

to transact any other business that may properly come before the special meeting and any adjournment or postponement of the special meeting.

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•

delivering to the Secretary of H Power a later-dated signed notice of revocation;

•

delivering to the Secretary of H Power a later-dated, signed proxy (which will automatically replace any earlier dated proxy card that you returned); or

•

attending the special meeting and voting in person.

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•

the fact that the proposed exchange ratio as of the last trading day prior to November 10, 2002 offered a premium of 106% to H Power’s stockholders relative to the then current stock price for H Power,

•

that given the competitive nature of the hydrogen fuel cell industry and H Power’s recent stock price performance, the exchange ratio gives H Power’s stockholders a value per share which may not be achievable within a reasonable time period; and

•

that the merger was therefore an attractive opportunity for H Power’s stockholders.

•

provide information to, and engage in discussion or negotiations with, a third party that makes an unsolicited superior proposal (as defined in the merger agreement); and

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•

withdraw or modify its recommendation that the stockholders vote in favor of adopting and approving the merger agreement and approving the merger.

•

increased visibility and market capitalization of the combined company;

•

increased financial strength of the combined company; and

•

greater intellectual property and technical resources of the combined company.

•

the merger agreement permits Plug Power to terminate the agreement if the H Power board of directors withdraws its recommendation in favor of the merger with Plug Power or recommends another proposal;

•

the merger agreement requires H Power to pay a termination fee to Plug Power if the merger agreement is terminated under some circumstances (See “—The Merger Agreement—Payment of Termination Fee and Expenses” on page 96);

•

risks associated with fluctuations in Plug Power’s stock price prior to the merger;

•

the risk of disruption of sales momentum and H Power’s operations as a result of uncertainties created by the announcement of the merger;

•

the interests of the directors and officers that are different from, or in addition to, those of H Power’s stockholders generally, including the receipt of change of control payments under the employment agreements with certain executive officers of H Power; and

•

other applicable risks described in the section of this joint proxy statement/prospectus entitled “Risk Factors” on page 27.

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•

the H Power board of directors’ familiarity with, and information provided by H Power’s management as to, the business, financial condition, results of operations, current business strategy and future prospects of H Power, as well as the risks involved in achieving those prospects and objectives in current industry and market conditions, the nature of the markets in which H Power operates, H Power’s position in such markets, and the historical and current market prices for H Power’s shares;

•

the information provided to the H Power board of directors by the officers of H Power and Lehman Brothers with respect to the financial aspects of the merger and the advantages of a combination of Plug Power and H Power from the point of view of H Power and its stockholders;

•

alternatives to the merger, as well as the risks, financial and otherwise, inherent in continuing as an independent public company in an industry that is changing rapidly as opposed to the strengths of a combination between Plug Power and H Power;

•

the process engaged in by H Power’s management and financial advisor, which included discussions with another merger candidate and financing institutions, enabled the H Power board of directors to have what it believed to be an accurate sense of the values that could be achieved in a third party transaction;

•

H Power’s need for financing, and the lack of definitive alternatives to the merger for available financing;

•

the review of the material terms and conditions of the merger as reflected in the merger agreement, including (1) the provisions permitting H Power to respond to unsolicited inquiries and proposals from, provide confidential information to, and participate in any discussions and negotiations with, third parties concerning sales of assets and mergers or similar transactions with H Power to the extent required to satisfy the fiduciary obligations of its directors; (2) the break-up fee; (3) the collar; and (4) the conditions precedent to the consummation of the merger, including regulatory approval and the estimated length of time to consummate the merger;

•

the premium offered to H Power’s stockholders relative to the current, historical and projected stock price for H Power, including the board’s conclusion that given the competitive nature of the fuel cell industry and H Power’s recent stock price performance, the exchange ratio gives H Power’s stockholders a value per share which may not be achievable within a reasonable time period and that the merger was thus an attractive opportunity for the stockholders;

•

the structure of the merger, which is intended to permit holders of H Power common stock to exchange all their shares of H Power common stock on a tax-free basis;

•

H Power’s low market capitalization, which further decreases financing options, and the fact that a higher market capitalization will provide the combined company with a wider array of financing options; and

•

the strategic options available to H Power, including the option of continuing to operate H Power as an independent, publicly-traded company, and the assessment of H Power’s board of directors that none of these options were reasonably likely to present superior opportunities, or were reasonably likely to create greater value for H Power’s stockholders, than the prospects presented by the merger.

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•

the merger agreement and the specific terms of the merger, including H Power’s right to terminate the merger agreement in certain situations if the product of (1) the anticipated number of shares of Plug Power common stock to be issued in the merger and (2) the reasonably anticipated average Plug Power common stock price is less than $29,675,000, the estimated net cash of H Power as of the closing of the merger;

•

publicly available information concerning H Power that Lehman Brothers believed to be relevant to its analysis, including H Power’s Annual Report on Form 10-K for the fiscal year ended May 31, 2002 and Quarterly Report on Form 10-Q for the quarter ended August 31, 2002;

•

publicly available information concerning Plug Power that Lehman Brothers believed to be relevant to its analysis, including Plug Power’s Annual Report on Form 10-K for the fiscal year ended December 31, 2001 and Quarterly Reports on Form 10-Q for the quarter ended March 31 and June 30, 2002;

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•

financial and operating information with respect to the business, operations and prospects of H Power furnished to Lehman Brothers by management of H Power, including financial projections of H Power on a stand-alone basis prepared by management of H Power;

•

H Power’s balance sheet, information with respect to H Power’s anticipated capital and investment expenditures, the likelihood that H Power would be able to meet its operating costs and capital requirements beyond October 2004, and the various capital market financing transactions that would be available to H Power on a stand-alone basis to fund its operations beyond October 2004;

•

financial and operating information with respect to the business, operations and prospects of Plug Power furnished to Lehman Brothers by management of Plug Power, including financial projections of Plug Power on a stand-alone basis prepared by management of Plug Power and financial projections of Plug Power after giving effect to the merger prepared by management of Plug Power and Plug Power’s representatives;

•

the trading histories of H Power’s common stock and Plug Power’s common stock from October 2001 to November 8, 2002 and a comparison of these trading histories with those of other companies in the fuel cell power source industry that Lehman Brothers deemed relevant;

•

a comparison of the historical financial results and present financial condition of H Power with those of other companies in the fuel cell power source industry that Lehman Brothers deemed relevant;

•

a comparison of the historical financial results and present financial condition of Plug Power with those of other companies in the fuel cell power source industry that Lehman Brothers deemed relevant;

•

the strategic benefits expected by Plug Power’s management and H Power’s management to result from a combination of the businesses of H Power and Plug Power;

•

the relative financial contributions of H Power and Plug Power to the combined company following consummation of the merger;

•

a possible liquidation of H Power, including the cash that would be distributed to H Power’s stockholders in connection with such liquidation;

•

a comparison of the strategic and competitive positions of H Power and Plug Power with those of other companies in the fuel cell power source industry that Lehman Brothers deemed relevant; and

•

a comparison of the financial terms of the merger with the financial terms of certain other recent transactions that Lehman Brothers deemed relevant.

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•

Plug Power;

•

Ballard Power;

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•

Hydrogenics;

•

Fuel Cell Energy;

•

Proton Energy; and

•

H Power.

•

FuelCell Energy, Inc.; and

•

Proton Energy Systems, Inc.

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•

Ballard Power Systems, Inc.; and

•

Hydrogenics Corp.

•

Financial resources of material strategic stockholders. Lehman Brothers considered the financial resources of the material strategic stockholders/partners of both Plug Power and H Power, as an indication of the strength of such stockholders/partners to provide distribution, operational, management and other support to Plug Power and H Power, respectively.

•

Implied equity support for power technology companies with well-known strategic and financial partners. Lehman Brothers considered that power technology companies with well-known strategic partners and investors, such as General Electric’s partnership with Plug Power and General Motors’ partnership with Hydrogenics, traded at a significant premium to power technology companies, such as H Power, without well-known strategic partners and investors as measured by firm value to revenues.

•

the prevalence in the current market of whole-company acquisition transactions in which consideration paid is less than or approximately equal to the “net cash” as shown on the acquisition target’s most recent publicly available balance sheet;

•

the premium of consideration paid in such transactions to pre-announcement trading prices of the target’s publicly traded stock price; and

•

the implied valuation multiples paid in such transactions.

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•

US RealTel Inc./Cypress Communications—January 10, 2002

•

Exelixis Inc./Genomica Corp—November 19, 2002

•

EM Holdings Inc./eMachines Inc.—November 9, 2001

•

Divine Inc./Eprise Corp—September 18, 2001

•

Cross Media Marketing/Lifeminders Inc.—July 19, 2001

•

Kana Communications/Broadbase Software Inc.—April 9, 2001

•

AmericanGreetings.com/Egreetings Network Inc.—February 5, 2001

•

iVillage Inc. – Women.com Networks—February 5, 2001

•

the premium per share paid by the acquiror compared to the share price of the target company prevailing (1) one day and (2) 30 days prior to the announcement of the transaction;

•

the premium per share paid by the acquiror compared to net cash on the target’s most recent publicly available balance sheet; and

•

the transaction equity value paid by the acquiror compared to the one year fiscal year forward projected revenues of the target company.

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•

the opinion of Stephens Inc., Plug Power’s financial advisor, to the effect that as of November 11, 2002, the exchange ratio set forth in the merger agreement was fair, from a financial point of view, to Plug Power;

•

H Power’s cash reserves and Plug Power’s belief that the addition of such cash to its own balance sheet would provide Plug Power with sufficient cash to help fund operations;

•

H Power’s intellectual property rights, technical resources and other assets;

•

the opportunity to preserve and enhance stockholder value by combining two complementary businesses;

•

the belief that the merger represents the most favorable alternative currently available to Plug Power to increase its capital resources and further its business objectives;

•

the belief that, while no assurances can be given, the merger is likely to be completed because of the limited nature of the closing conditions included in the merger agreement;

•

the belief that the merger agreement will likely be approved by H Power’s and Plug Power’s stockholders based upon (1) the premium offered to H Power’s stockholders relative to the current and historical price of H Power common stock and (2) the potential benefits of the merger to Plug Power and its stockholders identified by the board of directors as described in this section of the joint proxy statement/prospectus, including, in particular, the addition of H Power’s cash reserves to help fund Plug Power’s operations;

•

the benefits contemplated in connection with the merger, in particular the influx of capital resources, are likely to be achieved within a reasonable time frame;

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•

the belief that the combined company will be in a better position to continue to compete effectively in the fuel cell industry;

•

the terms of the merger agreement, including the ability of Plug Power to terminate the agreement if the H Power board of directors withdraws its recommendation in favor of the merger or approves or recommends any other acquisition proposal and the right to receive a $2,000,000 termination fee or to be reimbursed for Plug Power’s out-of-pocket expenses incurred in connection with the merger in the event that Plug Power terminates the merger agreement under certain circumstances;

•

the potential cost savings through the consolidation of businesses and the elimination of duplicative costs; and

•

the access to H Power’s portfolio of strategic partners and suppliers.

•

the risk that the potential benefits of the merger may not be realized, in part or at all, including the risk that H Power’s net cash at the effective time of the merger may be less than at the signing of the merger agreement or the date of the special meeting of Plug Power stockholders;

•

the risk that the merger may not be consummated, including the risks associated with obtaining the necessary approvals required to complete the merger, notwithstanding the voting agreements obtained from stockholders representing beneficial ownership of approximately 10.7% of H Power’s common stock as of January 6, 2003;

•

the risk of management and employee disruption associated with the merger, including the risk that despite the efforts of the combined company, key technical, marketing and management personnel might not remain employed by the combined company;

•

the potential costs the combined company may incur to (1) terminate, renegotiate or amend H Power’s existing obligations, including real estate and facility leases, (2) streamline the combined company’s business, (3) reduce excess capacity, including terminating employees and (4) eliminate redundant operations, including the consolidation of H Power’s operations into Plug Power’s headquarters in Latham, N.Y.;

•

the dilutive effect of the merger on Plug Power’s existing stockholders;

•

the risk that the merger could adversely affect Plug Power’s relationship with some of its existing or potential customers, suppliers or strategic partners;

•

the potential negative effect on Plug Power’s stock price as a result of the public announcement of the merger;

•

the significant costs involved in consummating the merger; and

•

other applicable risks described in this joint proxy statement/prospectus under “Risk Factors.”

•

the potential benefits and potential negative factors associated with the merger;

•

information concerning H Power’s business, financial performance and condition, particularly its cash position, operations, intellectual property, technology and management;

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•

the timing of the financing provided by the merger;

•

the relative inaccessibility and cost of other capital sources in the current economic environment;

•

current financial market conditions and historical market prices, volatility and trading information with respect to Plug Power common stock and H Power common stock;

•

the terms of the merger agreement and related agreements;

•

the potential impact of the merger on the customers, suppliers, strategic partners and employees of Plug Power and the combined company;

•

Plug Power’s management’s view as to the integration of H Power;

•

the results of the due diligence investigation conducted by Plug Power’s management, accountants, financial advisors and legal counsel;

•

the expected percentage ownership of the combined company by H Power’s stockholders;

•

the strategic and financial alternatives available to Plug Power;

•

the maturation cycle with respect to the fuel cell market generally;

•

advice of Plug Power’s outside legal counsel, on the proposed terms of the merger agreement; and

•

the analyses performed by Stephens, and its opinion (the full text of which is attached as Annex D to this joint proxy statement/prospectus).

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(1)

analyzed certain publicly available financial statements and reports regarding Plug Power and H Power;

(2)

analyzed certain internal financial statements and other financial and operating data concerning Plug Power and H Power prepared by the management of each;

(3)

analyzed, on a pro forma basis, the effect of the merger on Plug Power’s balance sheet, capitalization ratios, earnings and book value;

(4)

reviewed and compared the reported prices and trading activity for the H Power shares and Plug Power shares, with that of certain other comparable publicly-traded companies and their securities;

(5)

analyzed the assets, liabilities and operations of H Power;

(6)

reviewed, to the extent publicly available, certain comparable transactions;

(7)

reviewed the merger agreement and related documents;

(8)

discussed with the management of Plug Power the operations of, and future business prospects for, Plug Power and the anticipated financial consequences of the merger to Plug Power, including the expected costs of integrating H Power into Plug Power and any expected synergies;

(9)

assisted in Plug Power’s deliberations regarding the material financial terms of the merger and Plug Power’s negotiations with H Power; and

(10)

considered certain financial and strategic alternatives available to Plug Power.

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•

.58-.99 based on a ratio of market capitalization to net cash

•

.79-1.19 based on a ratio of market capitalization to book value

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Valueclick Inc. / Be Free Inc. – March 11, 2002

•

MCSi Inc. / Zengine Inc. – October 5, 2001

•

Divine Inc. / Eprise Corp. – September 18, 2001

•

Cross Media Marketing Corp. / Lifeminders Inc. – July 19, 2001

•

Verso Technologies Inc. / Telemate Net Software Inc. – May 7, 2001

•

Kana Software Inc. / Broadbase Software Inc. – April 9, 2001

•

74-.99 based on a ratio of transaction value to net cash

•

69-1.19 based on a ratio of transaction value to book value

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exchange  ratio  =

(the transaction value price ÷ average Plug Power common stock price) ÷ the total number of shares of H Power common stock outstanding immediately prior to the effective time of the merger.

•

between $6.47 and $5.29 (or equal to such prices), there is no change to the exchange ratio as derived from the formula above;

•

greater than $6.47, then the exchange ratio shall equal the exchange ratio that would be determined if the average Plug Power common stock price was $6.47; and

•

less than $5.29, then the exchange ratio shall equal the exchange ratio that would be determined if the average Plug Power common stock price was $5.29.

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•

If net cash of H Power (as determined in accordance with the merger agreement as discussed below) is less than $36,675,000, the transaction value price is adjusted to equal $50,675,000 minus the difference between $36,675,000 and the net cash;

•

If net cash of H Power is equal to $36,675,000, the transaction value price remains $50,675,000; and

•

If net cash of H Power is greater than $36,675,000, the transaction value price is adjusted to equal $50,675,000 plus the difference between net cash and $36,675,000.

•

The sum of:

¡

cash, cash equivalents and short term investments of H Power;

¡

15% of the amount by which H Power’s inventories exceed a value of $2,174,000 (up to a maximum addition of $30,000);

¡

$500,000, but only in the event Plug Power has received written confirmation of a specified payment of $500,000 in accordance with the ECO termination agreement (see “—Other Material Agreements Relating to the Merger—ECO Termination Agreement”); and

¡

the aggregate amounts, if any, of severance paid by H Power between November 11, 2002 through the effective time of the merger to specified employees (up to certain maximum amounts per employee);

•

less the sum of:

¡

current liabilities, excluding any current liabilities addressed in any of the bullet points below;

¡

amounts payable under the ECO termination agreement, other than specified payments aggregating $4,215,000;

¡

the aggregate amounts of liabilities of H Power and its subsidiaries that were not liabilities both existing as of November 11, 2002 and identified in the merger agreement, with certain specified exceptions for:

n

$180,000 in payment obligations under a specified consulting agreement;

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n

specified severance obligations; and

n

specified lease obligations;

¡

amounts payable pursuant to stay-bonus arrangements and specified management bonus arrangements, to the extent not accrued on the net cash statement (described below);

¡

amounts that H Power’s accounts receivable (including unbilled receivables and tax credit receivable), net of allowance for doubtful accounts, are less than $533,229 (up to a maximum amount of $293,000), excluding any accounts receivable with respect to Peugeot Citroen Automobiles S.A.;

¡

$360,000, unless Plug Power receives correspondence from an authorized individual at Peugeot stating that an account receivable existing as of November 11, 2002 in the amount of approximately $360,000 is valid and not in dispute, and Peugeot fully intends to pay the entire amount of the receivable;

¡

amounts that prepaid and other current assets are less than $1,191,359 (up to a maximum amount of $449,000);

¡

$35,000 for each of up to four specific fuel cell units to the extent H Power has not fully terminated the applicable service, maintenance and warranty obligations therefor;

¡

15% of the amount by which the aggregate value of H Power’s inventories is less than $2,174,000;

¡

any amounts which may be paid by H Power or Plug Power for an extended reporting period endorsement to the H Power directors and officers liability insurance coverage to the extent such amounts have not been paid by the effective time of the merger or resulted in an equivalent reduction in the total amount of cash and cash equivalents in the first bullet point above;

¡

amounts of liabilities as of November 11, 2002 that also exist as of the date the net cash statement is delivered to Plug Power which are attributable to binding obligations or commitments of H Power and its subsidiaries to purchase materials, components (including sub-systems) and replacement parts; and

¡

$180,284, unless Plug Power receives correspondence from an authorized individual at the National Institute of Standards and Technology (NIST) stating that H Power and its subsidiaries have no payment obligations to NIST.

•

is to be prepared in accordance with generally accepted accounting principles (GAAP) applied consistently with H Power’s past practices (other than for certain items that are specifically contemplated to be non-GAAP);

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•

is to explain in reasonable detail the calculation of the anticipated net cash as of the effective time of the merger; and

•

is to include reasonable supporting documentation.

•

the anticipated number of shares of Plug Power common stock to be issued in the merger, and

•

the reasonably anticipated average Plug Power common stock price. This is a distinct calculation from the determination of transaction value price. As described above the transaction value price is a value, initially set at $50,675,000, and which is adjusted by the difference between the net cash of H Power and $36,675,000.

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•

the right to receive any dividend or other distribution, if any, with respect to H Power common stock with a record date occurring prior to the effective time of the merger, and

•

the right to receive the merger consideration.

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•

Plug Power and its board of directors shall be substituted for H Power and the H Power board of directors or duly authorized board committee administering the H Power stock option plans;

•

each H Power stock option assumed by Plug Power will be exercisable solely for shares of Plug Power common stock;

•

the number of shares of Plug Power common stock subject to such H Power stock option will be equal to the number of shares of H Power common stock subject to such H Power stock option immediately prior to the effective time of the merger multiplied by the exchange ratio, rounded down to the nearest share;

•

the per share exercise price under each H Power stock option will be adjusted by dividing the per share exercise price under each such H Power stock option by the exchange ratio, rounded up to the nearest cent.

•

the corporate organization, existence, good standing and qualification to do business of H Power and its subsidiaries;

•

authorization of the merger agreement by H Power;

•

consents and approvals required to complete the merger;

•

H Power’s cash, cash equivalents and short-term investments;

•

litigation involving H Power and its subsidiaries;

•

changes in H Power’s and its subsidiaries’ business since May 31, 2002 and actions taken by H Power since May 31, 2002;

•

H Power’s and its subsidiaries’ liabilities;

•

H Power’s product and service warranty obligations;

•

H Power’s and its subsidiaries’ labor relations and employment matters; (+)

•

H Power’s and its subsidiaries’ material contracts;

•

the nature of the accounts receivables of H Power and its subsidiaries; (+)

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H Power’s and its subsidiaries’ accounting policies and management letters; (+)

•

the nature of specified relationships with customers, distributors and suppliers of H Power and its subsidiaries; (+)

•

product liability matters; (+)

•

the absence of specified business practices and of illegal transactions in securities by H Power’s directors and executive officers; (+)

•

intellectual property matters pertaining to H Power and its subsidiaries;

•

compliance with H Power’s cash investment policy; (+)

•

H Power’s and its subsidiaries’ ability to satisfy certain standards to increase the likelihood that the merger will be treated as a “reorganization” for federal income tax purposes; and

•

the accuracy of the information supplied by H Power in this joint proxy statement/prospectus.

•

compliance with applicable laws by H Power and its subsidiaries;

•

permits required to conduct H Power’s and its subsidiaries’ business and compliance with those permits;

•

the certificates of incorporation and bylaws of H Power and its subsidiaries;

•

H Power’s capitalization;

•

H Power’s subsidiaries;

•

H Power’s filings and reports with the Securities and Exchange Commission;

•

H Power’s consolidated financial statements;

•

H Power’s and its subsidiaries’ taxes;

•

H Power’s and its subsidiaries’ properties;

•

environmental matters pertaining to H Power and its subsidiaries;

•

H Power’s and its affiliates’ employee benefit plans;

•

payments required to be made by H Power and its subsidiaries to brokers and agents in connection with the merger;

•

the fairness opinion received by H Power from Lehman Brothers;

•

the vote of H Power stockholders required to approve the merger;

•

the inapplicability of anti-takeover laws to the merger;

•

H Power’s and its subsidiaries’ insurance coverage;

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the fact that neither H Power nor its affiliates owns any Plug Power common stock;

•

the absence of contracts with affiliates; and

•

the approval of the merger, the merger agreement and the contemplated transactions by H Power’s board of directors.

•

the corporate organization, existence, good standing and qualification to do business of Plug Power and its subsidiaries;

•

authorization of the merger agreement by Plug Power and Monmouth Acquisition Corp.;

•

Plug Power’s and Monmouth Acquisition Corp.’s capitalization;

•

consents and approvals required to complete the merger;

•

Plug Power’s filings and reports with the Securities and Exchange Commission;

•

Plug Power’s consolidated financial statements;

•

litigation involving Plug Power;

•

changes in Plug Power’s and its subsidiaries’ business since December 31, 2001;

•

intellectual property matters pertaining to Plug Power and its subsidiaries;

•

Plug Power’s and its subsidiaries’ material contracts;

•

Plug Power’s and its subsidiaries’ liabilities;

•

approvals of the merger agreement and the contemplated transactions by Plug Power’s board of directors; and

•

the accuracy of the information supplied by Plug Power in this joint proxy statement/prospectus.

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•

compliance with applicable laws by Plug Power and its subsidiaries;

•

permits required to conduct Plug Power’s and its subsidiaries’ business and compliance with those permits;

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the certificate of incorporation and bylaws of Plug Power and its subsidiaries;

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Plug Power’s subsidiaries;

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Plug Power’s and its subsidiaries’ taxes;

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environmental matters pertaining to Plug Power;

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Plug Power’s labor relations;

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payments required to be made by Plug Power and its subsidiaries to brokers and agents in connection with the merger;

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the fact that neither Plug Power nor its affiliates owns any H Power common stock; and

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the fairness opinion received by Plug Power from Stephens.

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splitting, combining, reclassifying, repurchasing, redeeming or otherwise acquiring any shares of its capital stock or other securities, except for dividends paid by a subsidiary to H Power or another of its subsidiaries;

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issuing or selling any of its stock or any other securities or equity equivalents, other than outstanding options;

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making any equipment purchases or capital expenditures in excess of $10,000 in the aggregate;

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acquiring, selling, leasing, licensing, encumbering, transferring or disposing of any of its assets;

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entering into, modifying or amending any agreement related to the licensing of its intellectual property assets;

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incurring any indebtedness or making any loan or advance;

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paying, discharging or satisfying any claim, liability or obligation, outside the ordinary course, or in excess of $5,000 in the aggregate;

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changing its accounting policies;

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making any tax elections or settling any material tax liability in excess of $10,000;

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except with respect to stay bonus agreements approved by Plug Power, adopting or amending any employee benefit plan or any agreement between H Power or its subsidiaries and their directors, officers or employees;

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increasing the compensation of any director, officer or employee;

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amending its organizational documents;

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authorizing a liquidation, dissolution, merger, consolidation, restructuring, recapitalization or reorganization;

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settling any pending or threatened litigation for an amount in excess of $15,000 in the aggregate;

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amending the term of any outstanding security;

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entering into, modifying, amending any existing or entering into any new material contract or otherwise subjecting H Power or its subsidiaries to any material commitment, obligation or liability, or entering into any contract or agreement requiring H Power or any of its subsidiaries to pay in excess of $10,000;

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licensing, assigning or otherwise transferring any rights to its intellectual property assets;

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permitting any of its or its subsidiaries’ insurance policies to be canceled;

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entering into any agreement with any customer or distributor related to the offering of discounts, extended warranties, service contracts, bundling of any products, rights of return or any other agreements or arrangements outside the ordinary course of business;

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amending or restating any of its Securities and Exchange Commission reports, except to the extent advised by H Power’s legal or accounting advisors that such action is required;

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taking any action which would make any of its representations and warranties untrue or incorrect; and

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agreeing to take any of the actions described above.

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solicit, initiate or encourage, including by way of furnishing non-public information, or take any other action to facilitate any inquiries or the making of any proposal that constitutes an acquisition proposal;

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participate in any discussion with, or otherwise communicate in any way with, any person relating to any acquisition proposal; or

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enter into any agreement regarding an acquisition proposal.

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adversely withdraw or modify, or propose to withdraw or modify, its approval or recommendation of the merger or the merger agreement;

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approve or recommend, or propose to approve or recommend, any other acquisition proposal;

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approve or recommend, or propose to approve or recommend, or execute or enter into a letter of intent or agreement relating to an acquisition proposal; or

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resolve to do any of the foregoing.

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tender offer, merger, consolidation or similar transaction involving H Power; or

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sale, lease or other disposition, directly or indirectly, by merger, consolidation, share exchange or otherwise, of any material assets or securities of H Power.

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the stockholders of H Power have not yet approved the merger agreement and the merger;

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the non-solicitation provisions described in this section have not been breached by H Power or its representatives; and

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the H Power board of directors determines in good faith, after consultation with its outside legal counsel, that failing to take such action would constitute a breach of its fiduciary duties under applicable law.

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the H Power board of directors determines in good faith, after consulting with its outside legal counsel and its financial advisor, would, if consummated, result in a transaction that is more favorable to the stockholders of H Power than the merger; and

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is for all of H Power’s common stock.

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a superior proposal is made and not withdrawn;

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neither H Power nor any of its representatives has breached the non-solicitation provisions of the merger agreement described above; and

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the board of directors of H Power concludes in good faith, after consultation with its outside legal counsel that, in light of the superior proposal, the withdrawal or modification of its recommendation is required in order for the H Power board of directors to comply with its fiduciary duties to H Power’s stockholders under applicable law.

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any change or event which it believes could reasonably be expected to cause any of its representations or warranties contained in the merger agreement to be untrue in any material respect; and

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any material failure of such party to comply with any covenant under the merger agreement.

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taking all actions necessary to obtain any necessary consents, approvals, orders, exemptions and authorizations by or from any public or private third party, including any that are required to be obtained under any federal, state or local law or regulation or any contract, agreement or instrument to which H Power or any of its subsidiaries is a party or by which any of their properties or assets are bound;

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to defend all lawsuits or other legal proceedings challenging the merger agreement or the consummation of the merger;

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to cause to be lifted or rescinded any injunction or restraining order or other order adversely affecting the ability of the parties to consummate the transactions contemplated in the merger agreement; and

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to effect all necessary registrations and filings and submissions of information requested by governmental authorities.

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deliver notice of “plant closing” compliant with the Worker Adjustment Retraining Act of 1986 (WARN Act) and expressly approved in writing by Plug Power to each employee and any other individual entitled to specific notice of H Power’s implementation of a “plant closing”; and

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deliver appropriate and effective notices of the closing of H Power’s Canadian facility, compliant with any and all Canadian or Quebec provincial laws similar to the WARN Act and expressly approved in writing by Plug Power to the Quebec Ministry of Labor, to each affected employee, and to any other entity with respect to which such notice is required or recommended under applicable law.

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incur or become subject to any liabilities, as described in the merger agreement,

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authorize, commit to or make any equipment purchases or capital expenditures, or

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acquire, sell, lease, license, encumber, transfer or dispose of any assets,

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will report directly to H Power’s board of directors;

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will be authorized up through the date of the effectiveness of the merger to take any and all actions as directed by the H Power board of directors, to implement cost saving measures and take other actions consistent with the objective of maximizing long-term cash preservation, taking into account Plug Power’s expectations of realizable cash following the integration of Plug Power and H Power; and

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is acceptable to Plug Power.

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the merger agreement must have been adopted and approved, and the merger must have been approved, by the requisite vote of the stockholders of H Power and the issuance of shares of Plug Power common stock in the merger pursuant to the merger agreement must have been approved by the requisite vote of the stockholders of Plug Power;