SecProbe.io

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Mail Stop 0308

April 20, 2005

VIA U.S. MAIL AND FACSIMILE

Mr. Joseph F. Pinkerton, III
Chief Executive Officer
Active Power, Inc.
2128 W. Braker Lane, BK12
Austin, TX 78758

			Re:	Active Power, Inc.
				Registration Statement on Form S-3
				File No. 333-123586
      Filed March 25, 2005

				Form 10-K and Form 10-K/A
				File No. 0-30939
				Filed March 15 and 23, 2005

Dear Mr. Pinkerton:

	We have limited our review to the disclosure in Item 9A of
the
annual report and the related certifications and have the
following
comments.  Where indicated, we think you should revise your
documents
in response to these comments.  If you disagree, we will consider
your explanation as to why our comment is inapplicable or a
revision
is unnecessary.  Please be as detailed as necessary in your
explanation.  In some of our comments, we may ask you to provide
us
with supplemental information so we may better understand your
disclosure.  After reviewing this information, we may or may not
raise additional comments.

	Please understand that the purpose of our review process is
to
assist you in your compliance with the applicable disclosure
requirements and to enhance the overall disclosure in your
filings.
We look forward to working with you in these respects.  We welcome
any questions you may have about our comments or on any other
aspect
of our review.  Feel free to call us at the telephone numbers
listed
at the end of this letter.

      Form S-3

Risk Factors, page 3
1. Given that your Form 10-K for the fiscal year ended December
31,
2004 discloses management`s conclusions that your disclosure
controls
and procedures and internal controls and procedures were not
effective as a result of a material weakness, consider including a
risk factor that describes the material weakness.  If you include
a
risk factor, you should disclose when the material weakness first
began, who identified the material weakness and discuss the
actions
taken and the additional steps you must take to remediate the
problem.  You should discuss your timetable for implementing these
changes.  Also, to the extent material, you should include
disclosure
in Management`s Discussion and Analysis in your annual report or
Form
S-3 describing the potential effects on your financial condition.

      Form 10-K for the Fiscal Year ended December 31, 2004
Item 9A. Controls and Procedures, page 47
Management`s Report on Internal Control Over Financial Reporting,
page 47
2. We note your statement that "[your] Chief Executive Officer and
Chief Financial Officer, concluded that, as of the end of the
period
covered by this report (December 31, 2004), [your] disclosure
controls and procedures were not effective in providing reasonable
assurance that information required to be disclosed by [you] in
the
reports filed or submitted by [you] under the Exchange Act is
recorded, processed, summarized and reported, within the time
periods
specified in the SEC`s rules and forms."  Please disclose
specifically when the material weakness was identified, the
parties
who identified the weakness and when the material weakness first
began.

Changes in Internal Control Over Financial Reporting, page 48
3. We note your disclosure "[e]xcept as described above, there has
been no change in our internal controls over financial reporting
during our most recent fiscal quarter that has materially
affected,
or is reasonably likely to materially affect, our internal
controls
over financial reporting."  Please revise to state clearly, if
correct, that there were changes in your internal control over
financial reporting that occurred during this quarter that have
materially affected, or are reasonably likely to materially
affect,
your internal control over financial reporting.

Form 10-K/A for the Fiscal Year ended December 31, 2004

Exhibits 31.1, 31.2, 31.3 and 31.4
4. Please amend your annual report to correct your certifications.
Please delete the title of the officer from the top and the first
sentence of each certification.  The top of the certificate and
the
first sentence of the exhibit should simply state the officer`s
name
without reference to his title or the name of the registrant.
Also,
the certifications should correspond exactly to the certifications
set forth in Item 601(b)(31) of Regulation S-K.  We note, for
example, that you have omitted language in paragraph 4.a. of your
certification.  Please re-file the entire Form 10-K with revised
certifications.

	*	*	*	*	*	*	*	*	*	*	*

      As appropriate, please amend your registration statement in
response to these comments.  You may wish to provide us with
marked
copies of the amendment to expedite our review.  Please furnish a
cover letter with your amendment that keys your responses to our
comments and provides any requested supplemental information.
Detailed cover letters greatly facilitate our review.  Please
understand that we may have additional comments after reviewing
your
amendment and responses to our comments.

      We urge all persons who are responsible for the accuracy and
adequacy of the disclosure in the filings reviewed by the staff to
be
certain that they have provided all information investors require
for
an informed decision.  Since the company and its management are in
possession of all facts relating to a company`s disclosure, they
are
responsible for the accuracy and adequacy of the disclosures they
have made.

	Notwithstanding our comments, in the event the company
requests
acceleration of the effective date of the pending registration
statement, it should furnish a letter, at the time of such
request,
acknowledging that:

?	should the Commission or the staff, acting pursuant to
delegated
authority, declare the filing effective, it does not foreclose the
Commission from taking any action with respect to the filing;

?	the action of the Commission or the staff, acting pursuant to
delegated authority, in declaring the filing effective, does not
relieve the company from its full responsibility for the adequacy
and
accuracy of the disclosure in the filing; and

?	the company may not assert staff comments and the declaration
of
effectiveness as a defense in any proceeding initiated by the
Commission or any person under the federal securities laws of the
United States.

	In addition, please be advised that the Division of
Enforcement
has access to all information you provide to the staff of the
Division of Corporation Finance in connection with our review of
your
filings or in response to our comments on your filings.

      We will consider a written request for acceleration of the
effective date of the registration statement as a confirmation of
the
fact that those requesting acceleration are aware of their
respective
responsibilities under the Securities Act of 1933 and the
Securities
Exchange Act of 1934 as they relate to the proposed public
offering
of the securities specified in the above registration statement.
We
will act on the request and, pursuant to delegated authority,
grant
acceleration of the effective date.

      We direct your attention to Rules 460 and 461 regarding
requesting acceleration of a registration statement.  Please allow
adequate time after the filing of any amendment for further review
before submitting a request for acceleration.  Please provide this
request at least two business days in advance of the requested
effective date.

	You may contact Scott Anderegg, Attorney, at (202) 942-2868,
Ellie Quarles, Special Counsel, at (202) 942-1859 or me at (202)
942-
1900 with any other questions.

      Sincerely,

      H. Christopher Owings
      Assistant Director

cc:	J. Matthew Lyons
	Andrews Kurth LLP
	VIA FAX

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Mr. Joseph F. Pinkerton, III
Active Power, Inc.
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