NOVELTY - Redox fuel cell comprises: an anode and a cathode separated by an ion selective polymer electrolyte membrane; means for supplying a fuel to the anode region of the cell; means for supplying an oxidant to the cathode region of the cell; means for providing an electrical circuit between the anode and the cathode; and a non-volatile catholyte solution flowing fluid communication with the cathode. The catholyte solution comprises a polyoxometalate redox couple that is at least partially reduced at the cathode in operation of the cell.    USE - The redox fuel cell is useful in micro fuel cells for electronic and portable electronic components, and in larger fuel cells for the automotive industry and for stationary applications.    ADVANTAGE - The redox fuel cell: utilizes the catholyte solution, thus producing a higher sustainable current; utilizes vanadium containing polyoxometalate solution, thus exhibiting improved performance; and avoids expensive cathodic materials, thus is cost effective.    DETAILED DESCRIPTION - Redox fuel cell comprises: an anode and a cathode separated by an ion selective polymer electrolyte membrane; means for supplying a fuel to the anode region of the cell; means for supplying an oxidant to the cathode region of the cell; means for providing an electrical circuit between the anode and the cathode; and a non-volatile catholyte solution flowing fluid communication with the cathode. The catholyte solution comprises: a polyoxometalate redox couple that is at least partially reduced at the cathode in operation of the cell, and at least partially regenerated by reaction with the oxidant after the reduction at the cathode; at least 0.075M of the polyoxometalate of formula (X1a(Z1bM1cOd)); and vanadium(IV) compound.    X1 = H, alkali metal, alkaline earth metal, ammonium and/or alkyl ammonium;    Z1 = B, P, S, As, Si, Ge, Ni, Rh, Sn, Al, Cu, I, Br, F, Fe, Co, Cr, Zn, H, Te, Mn and/or Se;    M1 = Mo, W, V, Nb, Ta, Mn, Fe, Co, Cr, Ni, Zn Rh, Ru, Tl, Al, Ga, In and/or other metals comprising first, second, third transition metal series and lanthanide series, or at least one Vanadium atom;    a = a number of X1 necessary to charge balance the (Z1bMcOd) anion;    b = 0-20;    c = 1-40; and    d = 1-180.    An INDEPENDENT CLAIM is also included for the catholyte solution.