September 10, 2018

Donald Young
Chief Executive Officer
Aspen Aerogels, Inc.
30 Forbes Road, Building B
Northborough, MA 01532

       Re: Aspen Aerogels, Inc.
           Registration Statement on Form S-3
           Filed August 31, 2018
           File No. 333-227158

Dear Mr. Young:

       This is to advise you that we have not reviewed and will not review your
registration
statement.

        Please refer to Rules 460 and 461 regarding requests for acceleration.
We remind you
that the company and its management are responsible for the accuracy and
adequacy of their
disclosures, notwithstanding any review, comments, action or absence of action
by the staff.

       Please contact Kate McHale at (202) 551-3464 with any questions.



                                                            Sincerely,

                                                            Division of
Corporation Finance
                                                            Office of
Manufacturing and
                                                            Construction