August 13, 1997
                                                                       
Catalytica, Inc. 
430 Ferguson Drive
Mountain View, California 94043

     RE:   REGISTRATION STATEMENT ON FORM S-8
           ---------------------------------

Gentlemen:

     We have examined the Registration Statement on Form S-8 to be filed by you
with the Securities and Exchange Commission on August 14, 1997 (the
"Registration Statement"), in connection with the registration under the
Securities Act of 1933, as amended, of 2,700,000 shares of your Common Stock
reserved for issuance under the 1992 Stock Option Plan and the 1992 Employee
Stock Purchase Plan and the 1995 Director Option Plan (the "Plans").  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 such Common Stock under the Plans.

     It is our opinion that, when issued and sold in the manner referred to in 
the Plan and pursuant to the agreements which accompany the Plan, the Common
Stock issued and sold thereby will be legally and validly issued, fully paid and
non-assessable.

     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 any Prospectus constituting a part thereof,
and any amendments thereto.

                                        Very truly yours,

                                        WILSON, SONSINI, GOODRICH & ROSATI
                                        Professional Corporation