A process for the reductive deposition of polyoxometallate complexes on supports. The process includes the steps of forming a solution of at least one polyoxometallate compound in a solvent, said compound having the formula A.sub.a (L.sub.l M.sub.m J.sub.z O.sub.y), adding a quantity of a support material having electronic conductivity to the solution, charging the solution containing the support material to an electrolytic cell in contact with the cathode thereof, the cell having a separate compartment for the anode, passing a current of from about 0.1 to about 500 mA/cm.sup.2 of electrode area through the cell whereby the support material receives a deposit of a polyoxometallate wherein the average oxidation state of the metals therein has been reduced to a valence greater than zero and, thereafter separating and recovering the support material carrying the reduced metallate complex.