NOVELTY - Solid polymer electrolyte membrane (I) comprises: (a) an ion exchange material (11); and (b) a hydrogen peroxide decomposition catalyst bound to a carbon particle support, dispersed in the ion exchange material, where the hydrogen peroxide decomposition catalyst comprises polyvinylphosphonic acid and cerium.    USE - (I) is useful in electrodes, catalyst coated membranes and fuel cells (all claimed).    ADVANTAGE - (I) has reduced membrane degradation and increased membrane life, due to the presence of the compounds (A) as a component in solid polymer electrolyte membranes. (I) is highly stable.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a compound (A) for increasing the durability of a membrane comprising: (c) an organic polymer comprising a monomer with at least two carbon atoms and at least one moiety comprising phosphorus or dihydrogen phosphate; and (d) a metal comprising a transition or lanthanide metal with multiple oxidation states;    (2) a composition comprising the reaction product of carbon black, polyvinylphosphonic acid (PVPA), cerium(III)nitrate hexahydrate and water;    (3) an electrode for use in a solid polymer electrolyte fuel cell comprising: (a) an ion exchange material; (c); (d); and (e) a catalyst for either fuel oxidation or oxygen reduction;    (4) a catalyst coated membrane comprising: at least one electrode capable of oxidizing a fuel or reducing an oxidant; and a solid polymer electrolyte attached to the electrode;    (5) a fuel cell comprising: an anode comprising a catalyst for oxidizing fuel; a cathode comprising a catalyst for reducing an oxidant; a solid polymer electrolyte, where at least one of the solid polymer electrolyte, the anode and the cathode comprises a peroxide decomposition catalyst; a fuel supplied to the anode; and an oxidant supplied to the cathode; and    (6) a method to make a compound comprising: preparing an organic polymer comprising at least two carbon atoms in solution; adding a salt of a metal comprising a transition or lanthanide with multiple oxidation states; and precipitating the compound.    DESCRIPTION OF DRAWING(S) - The diagram shows the solid polymer electrolyte.    Ion exchange material (11)    Electronically insulating ionomer layer (13)    Many particles. (14)