EXHIBIT 5.1



June 6, 2002

MOCON, Inc.
7500 Boone Avenue North
Minneapolis, MN 55428

RE:      MOCON, INC. REGISTRATION STATEMENT ON FORM S-8

Ladies/Gentlemen:

We have acted as counsel to MOCON, Inc., a Minnesota corporation (the
"Company"), in connection with the registration by the Company of an additional
550,000 shares of common stock, $.10 par value per share (the "Shares"), of the
Company issuable under the Company's 1998 Stock Option Plan (the "Plan")
pursuant to a Registration Statement on Form S-8 to be filed with the Securities
and Exchange Commission on June 6, 2002 (the "Registration Statement").

In acting as counsel for the Company and arriving at the opinions expressed
below, we have examined and relied upon originals or copies, certified or
otherwise identified to our satisfaction, of such records of the Company,
agreements and other instruments, certificates of officers and representatives
of the Company, certificates of public officials and other documents as we have
deemed necessary or appropriate as a basis for the opinions expressed herein. In
connection with our examination, we have assumed the genuineness of all
signatures, the authenticity of all documents tendered to us as originals, the
legal capacity of all natural persons and the conformity to original documents
of all documents submitted to us as certified or photostatic copies.

Based on the foregoing, and subject to the qualifications and limitations stated
herein, it is our opinion that:

1.   The Company has the corporate authority to issue the Shares in the manner
     and under the terms set forth in the Registration Statement.

2.   The Shares have been duly authorized and, when issued, delivered and paid
     for in accordance with the Plan as set forth in the Registration Statement,
     will be validly issued, fully paid and nonassessable.

We express no opinion with respect to laws other than the laws of the State of
Minnesota and the federal laws of the United States of America, and we assume no
responsibility as to the applicability thereto, or the effect thereon, of the
laws of any other jurisdiction.

We hereby consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement and to its use as part of the Registration Statement.

Very truly yours,

OPPENHEIMER WOLFF & DONNELLY LLP

/s/ Oppenheimer Wolff & Donnelly LLP