NOVELTY - A redox fuel cell comprises an anode and a cathode separated by an ion selective polymer electrolyte membrane; unit for supplying a fuel to the anode region of the cell; unit for supplying an oxidant to the cathode region of the cell; unit for providing an electrical circuit between the anode and the cathode; a non-volatile catholyte solution flowing fluid communication with the cathode.    USE - The redox fuel cell is useful for producing electricity (claimed); and used in microfuel cells for electronic and portable electronic components, and also in larger fuel cells for the automotive industry.    ADVANTAGE - The redox fuel cell is cost-effective, uses environment friendly materials, has maintainable current densities and/or cell potentials, and does not produce unwanted by-products and/or pollutants.    DETAILED DESCRIPTION - A redox fuel cell comprises an anode and a cathode separated by an ion selective polymer electrolyte membrane; unit for supplying a fuel to the anode region of the cell; unit for supplying an oxidant to the cathode region of the cell; unit for providing an electrical circuit between the anode and the cathode; a non-volatile catholyte solution flowing fluid communication with the cathode, the catholyte solution comprising a polyoxometallate redox couple being at least partially reduced at the cathode in operation of the cell, and at least partially regenerated by reaction with the oxidant after such reduction at the cathode, where the polyoxometallate is represented by the formula: Xa(ZbMcOd).    X=hydrogen, alkali metals, alkaline earth metals, ammonium and combinations of two or more;    Z=B, P, S, As, Si, Ge, Ni, Rh, Sn, Al, Cu, I, Br, F, Fe, Co, Cr, Zn, H2, Te, Mn and Se and combinations of two or more;    M=W and optionally one or more of Mo, V, Nb, Ta, Mn, Fe, Co, Cr, Ni, Zn Rh, Ru, Tl, Al, Ga, In and other metals selected from the 1st, 2nd and 3rd transition metal series and the lanthanide series;    a=a number of X necessary to charge balance the (ZbMcOd) anion;    b=0-5;    c=5-30; and    d=1-180.    An INDEPENDENT CLAIM is a method of operating the fuel cell, comprising: (a) forming H+ ions at an anode situated adjacent to an ion selective polymer electrolyte membrane; (b) supplying the catholyte with its redox couple in an oxidized state to a cathode situated oppositely adjacent to the ion selective polymer electrolyte membrane; (c) allowing the catalyst to become reduced upon contact with the cathode concomitantly with H+ ions passing through the membrane to balance charge; (d) optionally, passing the catholyte from the cathode to a reoxidation zone where the catalyst is reoxidized; and (e) optionally, passing the catholyte from the reoxidation zone to the catholyte reservoir.