Initial Statement of Beneficial Ownership (3)

LIMITED POWER OF ATTORNEY FOR SECTION 16 REPORTING OBLIGATIONS

 
      The undersigned hereby constitutes and appoints each of Michael D. Grover,
Sonia M. Dumbleton and Kevin B. Klotzbach as the undersigned's true and lawful
attorney-in-fact, and grants each of them full power to act on behalf of the
undersigned and in the undersigned's name, place and stead, for the purpose of
completing and signing, on behalf of the undersigned, any Form 3, Form 4 or Form
5 (including any amendments thereto) required or permitted to be filed by the
undersigned pursuant to Section 16 of the Securities Exchange Act of 1934, as
amended (the Exchange Act"), with regard to the undersigned's holdings of or
transactions in the securities of Financial Institutions, Inc., and to file such
forms (and amendments thereto) with the Securities and Exchange Commission, and
to do and perform each and every act and thing requisite or necessary to be done
in connection with such forms (and amendments thereto,) as fully and to all
intents and purposes as the undersigned might or could do in person.
      
      The authority of Michael D. Grover, Sonia M. Dumbleton and Kevin B.
Klotzbach under this Limited Power of Attorney shall continue until the
undersigned is no longer required to file forms under Section 16(a) of the
Exchange Act with regard to the undersigned's holdings of or transactions in the
securities of Financial Institutions, Inc., unless earlier revoked by the
undersigned in writing.
      
      The undersigned acknowledges that Michael D. Grover, Sonia M. Dumbleton
and Kevin B. Klotzbach are not assuming any of the undersigned's
responsibilities to comply with Section 16 of the Exchange Act.


/s/ Charles J. Guarino
Signature
Name:  Charles J. Guarino
Date:  January 27, 2016