CERTIFICATION PURSUANT TO RULE 30A-2(B) UNDER THE 1940 ACT AND
                      SECTION 906 OF THE SARBANES-OXLEY ACT

I,  Donald F.  Crumrine,  Director,  Chairman  of the Board and Chief  Executive
Officer  of  Flaherty  & Crumrine Preferred Income Opportunity Fund Incorporated
(the "Registrant"), certify that:

         1.     The Form N-CSR of the Registrant  (the "Report")  fully complies
                with  the   requirements  of  Section  13(a)  or  15(d)  of  the
                Securities Exchange Act of 1934, as amended; and

         2.     The information  contained in the Report fairly presents, in all
                material  respects,  the  financial  condition  and  results  of
                operations of the Registrant.


Date:    JULY 23, 2007                            /S/ DONALD F. CRUMRINE
     -----------------------           -----------------------------------------
                                       Donald F. Crumrine, Director, Chairman of
                                       the Board and Chief Executive Officer
                                       (principal executive officer)


I, R. Eric Chadwick,  Chief  Financial Officer, Treasurer, and Vice President of
Flaherty  &  Crumrine  Preferred  Income  Opportunity  Fund  Incorporated   (the
"Registrant"), certify that:

         1.     The Form N-CSR of the Registrant  (the "Report")  fully complies
                with  the   requirements  of  Section  13(a)  or  15(d)  of  the
                Securities Exchange Act of 1934, as amended; and

         2.     The information  contained in the Report fairly presents, in all
                material  respects,  the  financial  condition  and  results  of
                operations of the Registrant.


Date:    JULY 23, 2007                            /S/ R. ERIC CHADWICK
     -----------------------          ------------------------------------------
                                      R. Eric Chadwick, Chief Financial Officer,
                                      Treasurer and Vice President
                                      (principal financial officer)