EXHIBIT 5.1
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                               [WSGR LETTERHEAD]



                                August 8, 1997



Catalytica, Inc.
430 Ferguson Drive
Mountain View, California  94043

     RE:  REGISTRATION STATEMENT ON FORM S-3
 
Ladies and Gentlemen:

     We have examined the Registration Statement on Form S-3 to be filed by you
with the Securities and Exchange Commission on July 31, 1997 (as such may
thereafter be amended or supplemented, the "Registration Statement"), in
connection with the registration under the Securities Act of 1933, as amended,
of up to 7,566,319 warrants to purchase Common Stock (the "Warrants") and the
7,566,319 shares of your Common Stock, $0.001 par value (the "Shares") issuable
upon exercise of the Warrants.  As your legal counsel, we have examined the
proceedings taken, and are familiar with the proceedings proposed to be taken,
by you in connection with the sale and issuance of the Warrants and the Shares.

     It is our opinion that, upon completion of the proceedings being taken or
contemplated by us, as your counsel, to be taken prior to the issuance of the
Warrants and Shares, the Warrants and Shares, when issued and sold in the manner
described in the Registration Statement and in accordance with the resolutions
adopted by the Board of Directors of the Company, 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, including the Prospectus constituting a part thereof,
and any amendments thereto.

                              Very truly yours,

                              WILSON SONSINI GOODRICH & ROSATI
                              Professional Corporation

                              /s/ Wilson Sonsini Goodrich & Rosati