EXHIBIT 32.2

           CERTIFICATION PURSUANT TO RULE 13a-14(b) OR RULE 15d-14(b)
       OF THE SECURITIES EXCHANGE ACT OF 1934 AND 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 on Form 10-K of Penwest
Pharmaceuticals Co. (the "Company") for the year ended December 31, 2003 as
filed with the Securities and Exchange Commission on the date hereof (the
"Report"), the undersigned, Jennifer L. Good, Chief Financial Officer of the
Company, hereby certifies, pursuant to 18 U.S.C. Section 1350, that:

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

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

Dated: March 9, 2004      /s/ Jennifer L. Good
                          ----------------------------------
                          Jennifer L. Good
                          Sr. Vice President,Finance and Chief Financial Officer
                          (Chief Financial Officer)