QuickLinks -- Click here to rapidly navigate through this document

Exhibit 32.1

CERTIFICATION PURSUANT TO
18 U.S.C. SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

        In connection with the Annual Report of Innovative Solutions and Support, Inc. (the "Company") on Form 10-K for the period ending September 30, 2007 as filed with the Securities and Exchange Commission on the date hereof (the "Report"), each of the undersigned officers of the Company, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that:

        (1)   The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

        (2)   The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/  RAYMOND J. WILSON Raymond J. Wilson
Chief Executive Officer and Director
December 12, 2007

/s/  JAMES J. REILLY James J. Reilly
Chief Financial Officer
December 12, 2007

QuickLinks

Exhibit 32.1