EXHIBIT 5.1

                              September 23, 1999

Catalytica, Inc.
430 Ferguson Drive
Mountain View, CA 94043-5272

     RE:  REGISTRATION STATEMENT ON FORM S-8

Ladies and Gentlemen:

     We have acted as counsel to Catalytica, Inc., a Delaware corporation (the
"Company" or "you") and have examined the Registration Statement on Form S-8
(the "Registration Statement") to be filed by the Company with the Securities
and Exchange Commission on or about September 23, 1999, in connection with the
registration under the Securities Act of 1933, as amended, of 466,674 shares of
the Company's Common Stock, par value $0.001 per share (the "Shares"), reserved
for issuance under the Wyckoff Chemical Company, Inc. 1993 Stock Option Plan and
the Wyckoff Chemical Company, Inc. Stock Bonus Plan (collectively, the "Plans").
As your legal counsel, we have examined the Restated Certificate of
Incorporation and Bylaws of the Company, the Plans and such other documents of
the Company as we have deemed necessary or appropriate for the purposes of the
opinion expressed herein, and are familiar with the proceedings proposed to be
taken by you in connection with the operation and administration of the Plans
and the sale and issuance of the Shares pursuant to the Plans.

     In our opinion, the Shares, when issued and sold in the manner referred to
in the Plans and pursuant to the agreements which accompany the Plans, will be
legally and validly issued, fully paid and nonassessable.

     We consent to the use of this opinion as an exhibit to the Registration
Statement and further consent to the use of our name wherever appearing in the
Registration Statement and any subsequent amendment thereto.

                                        Very truly yours,

                                        WILSON SONSINI GOODRICH & ROSATI
                                        Professional Corporation

                                        /s/ Wilson Sonsini Goodrich & Rosati