SecProbe.io

January 13, 2012
 Via E-mail

Richard Rutkowski Chief Executive Officer ClearSign Combustion Corporation 12870 Interurban Avenue South Seattle, Washington 98168
Re: ClearSign Combustion Corporation
 Amendment No. 1 to Registra tion Statement on Form S-1
Filed December 28, 2011
  File No. 333-177946

Dear Mr. Rutkowski:

We have reviewed your registration statem ent and have the following comments.  In
some of our comments, we may ask you to provi de us with information so we may better
understand your disclosure.
 Please respond to this letter by amending your registration statement and providing the
requested information.  If you do not believe  our comments apply to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why in your
response.
 After reviewing any amendment to your re gistration statement and the information you
provide in response to these comments , we may have additional comments.
 Prospectus Cover Page

1. We note your revised disclosure in response to  prior comment 2 that “although a specific
price cannot be determined at this time,” you have “estimated an initial price” of $4.00
per share.  From the disclosure, it remains unclear whether the offering price has been
fixed.  Please revise to clarify, if true, th at the offering price has been fixed at $4.00.
 The Industry, page 1

 2. We note your response to prior comment 9; how ever, it is unclear from the materials
provided in response to the comment how you estim ated the value of the capital assets in
the United States relating to combus tion of hydrocarbon and other fuels.

Richard Rutkowski ClearSign Combustion Corporation January 13, 2012 Page 2

 The Offering, page 6

 3. We note your response to prior comment 15.  He re and in the “Use of Proceeds” section
beginning on page 65, please revise to qua ntify the approximate amount of proceeds
intended to be used for each purpose.
 System Results, page 22

 4. We note your response to prior comment 16 and your revised disclosu re on pages 22 - 25.
Please revise to disclose how many experi ments were conducted and how often the
observed results occurred.  Also, please demonstrate to us that your testing produced
statistically significant results.
Research and Development Plan, page 25

 5. We note your response to prior comment 18; however, you have not disclosed the costs
associated with completing each bullet point.  Please revise accordingly.
 Competitive Advantage, page 38

6. We note your response to prior comment 21; however, we continue to note a number of
statements in this section that definitively  describe your product as producing a certain
result compared to existing t echnology.  It is unclear why yo u believe it is appropriate to
retain such statements based on your current stage of development. As such, we reissue
prior comment 21.
 Underwriting Discounts and Expenses, page 62

 7. Please expand your disclosure to describe in more detail the agreement to pay the
underwriters a non-accountable expense al lowance equal to $160,000, including what
expenses are covered in this agreement.  Also, please tell us where you have filed this
agreement as an exhibit.
 Financial Statements, page F-1

 Note 8 - Subsequent Events, page F-21

 8. We note your disclosure that “all share and pe r price information has been retroactively
adjusted to reflect the stock split” that  was effective December 22, 2011.  Please tell us
how the financial statements in this filing ha ve been retroactively adjusted for the stock
split. Refer to the guidance in SAB T opic 4.C and FASB ASC 260-10-55-12.

Richard Rutkowski ClearSign Combustion Corporation January 13, 2012 Page 3

 Exhibit 5.1

 9. Please tell us why the opinion as to the sel ling stockholder shares is qualified to the
declaration of effectiveness of the registration statement.

We urge all persons who are responsible for th e accuracy and adequacy of the disclosure
in the filing to be certain that the filing incl udes the information the Securities Act of 1933 and
all applicable Securities Act rules require.  Since the company and its management are in
possession of all facts relating to a company’s disc losure, they are responsible for the accuracy
and adequacy of the disclosures they have made.
Notwithstanding our comments, in the event you request acceleration of  the effective date
of the pending registration statement please pr ovide a written statement from the company
acknowledging that:
 should the Commission or the staff, acting purs uant to delegated authority, declare the
filing effective, it does not foreclose the Co mmission 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 a nd 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.

Please refer to Rules 460 and 461 regarding re quests for acceleration.  We will consider a
written request for acceleration of  the effective date of the regi stration statement as confirmation
of the fact that those reques ting acceleration are aware of thei r respective responsibilities under
the Securities Act of 1933 and the Securities Excha nge Act of 1934 as they relate to the proposed
public offering of the securities specified in th e above registration stat ement.  Please allow
adequate time for us to review any amendment prior to the requested effective date of the
registration statement.

Richard Rutkowski ClearSign Combustion Corporation January 13, 2012 Page 4

 You may contact Praveen Kart holy at 202-551-3778 or Brian Cascio, Accounting Branch
Chief, at 202-551-3676 if you have questions rega rding comments on the financial statements
and related matters.  Please contact Jay Mumf ord at 202-551-3637 or Mary Beth Breslin, Senior
Attorney, at 202-551-3625 w ith any other questions.

Sincerely,

 /s/ Russell Mancuso
        R u s s e l l  M a n c u s o          B r a n c h  C h i e f    cc (via e-mail): Kevin Friedmann, Esq.