Filed by Plug Power Inc.
             Pursuant to Rule 425 under the Securities Act of 1933, as amended.

                                                 Subject Company: H Power Corp.
                                                 Commission File No. 333-101567
[H POWER LOGO APPEARS HERE]

                                 H POWER CORP.
                             60 Montgomery Street
                         Belleville, New Jersey 07109
                                (973) 450-4400

                            AN IMPORTANT REMINDER!

March 3, 2003

Dear Stockholder:

   We have previously mailed you proxy materials in connection with the
upcoming special meeting of H Power stockholders, which has been called to vote
upon a proposed merger of H Power with Plug Power. The meeting is scheduled to
be held on Tuesday, March 25, 2003. According to our latest records, your proxy
instructions for this meeting have not yet been received.

   Your Board of Directors recommends that stockholders vote in favor of the
proposal to adopt and approve the Agreement and Plan of Merger, a copy and the
material details of which are included in the proxy material previously sent to
you, dated February 12, 2003. PLEASE PROMPTLY TAKE ACTION TO ENSURE THAT YOUR H
POWER SHARES ARE REPRESENTED AT THE SPECIAL MEETING.

   Your vote is very important, regardless of the number of H Power shares you
currently own. Since the time until the special meeting is short, we urge you
to vote your shares today, by following either the telephone or internet voting
instructions that are enclosed with this letter. You may also sign, date, and
return the enclosed voting instruction form in the envelope provided. Acting
now will help ensure that your proxy instructions are received in time for the
meeting. Thank you for your prompt attention.

   IF YOU OWN YOUR H POWER SHARES IN STREET NAME, PLEASE TAKE NOTE THAT YOUR
BROKER CANNOT VOTE YOUR SHARES FOR YOU ON THIS PROPOSAL WITHOUT FIRST RECEIVING
YOUR SPECIFIC VOTING INSTRUCTIONS. THANK YOU FOR GIVING THIS IMPORTANT MATTER
YOUR PROMPT ATTENTION.


                                                  Sincerely,

                                                  /s/ H. Frank Gibbard
                                                  ------------------------
                                                  Dr. H. Frank Gibbard
                                                  Chief Executive Officer



         Additional Information About the Merger and Where to Find It.

   On February 12, 2003, Plug Power filed a registration statement with the SEC
containing a definitive joint proxy statement/prospectus regarding the proposed
merger with H Power. On or about February 13, 2003, Plug Power and H Power
mailed the joint proxy statement/prospectus to their respective stockholders in
connection with the proposed merger. INVESTORS AND SECURITY HOLDERS OF PLUG
POWER AND H POWER ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS AND
ANY OTHER RELEVANT MATERIALS FILED BY PLUG POWER OR H POWER WITH THE SEC
BECAUSE THEY CONTAIN, OR WILL CONTAIN, IMPORTANT INFORMATION ABOUT PLUG POWER,
H POWER AND THE MERGER. Investors and security holders may obtain a copy of the
joint proxy statement/prospectus (and other relevant materials when they become
available) at the SEC's web site, www.sec.gov. The joint proxy
statement/prospectus (and other relevant materials when they become available)
may also be obtained free of charge from Plug Power by directing a request to
Plug Power at 968 Albany-Shaker Road, Latham, NY 12110, Attention: Roger
Saillant, President; and from H Power by directing a request to H Power at 60
Montgomery Street, Belleville, New Jersey, 07109, Attention: William L. Zang.
In addition to the registration statement that has been filed by Plug Power in
connection with the transaction, and the joint proxy statement/prospectus
mailed to the stockholders of Plug Power and H Power, each of Plug Power and H
Power files annual, quarterly and special reports, proxy statements and other
information with the SEC. Investors and security holders may read and copy any
of these reports, statements and other information at the SEC's public
reference rooms located at 450 5th Street, N.W., Washington, D.C., 20549, or
any of the SEC's other public reference rooms. Investors and security holders
should call the SEC at 1-800-SEC-0330 for further information on these public
reference rooms. The reports, statements and other information filed by Plug
Power and H Power with the SEC are also available for free at the SEC's web
site at www.sec.gov. A free copy of these reports, statements and other
information may also be obtained from Plug Power and H Power.

   Plug Power, H Power and their respective executive officers and directors
may be considered participants in the solicitation of proxies from the
stockholders of Plug Power and H Power in favor of the merger. A description of
the interests of Plug Power's executive officers and directors in Plug Power is
set forth in the joint proxy statement/prospectus. A description of the
interests of H Power's executive officers and directors in H Power is also set
forth in the joint proxy statement/prospectus.