EXHIBIT 99.1

                            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 Quarterly Report of Neose Technologies, Inc. (the
"Company") on Form 10-Q for the period ending March 31, 2003 as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), I, C. Boyd
Clarke, President and Chief Executive Officer of the Company, certify, pursuant
to 18 U.S.C. Section 1350, as adopted pursuant to Section 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.

A signed original of this written statement required by Section 906 has been
provided to Neose Technologies, Inc. and will be retained by Neose Technologies,
Inc. and furnished to the Securities and Exchange Commission or its staff upon
request.

/s/ C. Boyd Clarke
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C. Boyd Clarke
President and Chief Executive Officer

May 13, 2003