NOVELTY - A ternary catalyst for use in oxidation or reduction reactions, comprises platinum (less than 50 atomic %), nickel, and manganese or iron.    USE - The catalyst is used in oxidation or reduction reactions. It is used in electrochemical reactor devices; and in fuel cell electrodes useful in fuel cells (claimed) e.g. electrocatalyst. The fuel cell is used in electrical utility power generation facilities, uninterrupted power supply devices, extraterrestrial vehicles, transportation equipment such as heavy trucks, automobiles and motorcycles, residential power generation system, mobile communication equipment such as wireless telephones, pagers and satellite phones, mobile electronic devices such as laptop computers, personal data assistants, audio recording and/or playback devices, digital cameras, digital video cameras, and electronic game playing devices, military and aerospace equipment such as global positioning satellite devices, and robots.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a supported electrocatalyst powder for use in electrochemical reactor devices, comprising the ternary catalyst and electrically conductive support particles upon which the ternary catalyst is dispersed;    (2) a fuel cell electrode (2, 3) comprising electrocatalyst particles and an electrode substrate upon which the electrocatalyst particles are deposited, the electrocatalyst particles comprising the ternary catalyst; and    (3) a fuel cell (21) comprising an anode, a cathode, a proton exchange membrane (1) between the anode and the cathode, and the ternary catalyst for the catalytic oxidation of a hydrogen-containing fuel or the catalytic reduction of oxygen;    (4) a method for the electrochemical conversion of a hydrogen-containing fuel and oxygen to reaction products and electricity in a fuel cell;    (5) an unsupported ternary catalyst layer on the surface of an electrolyte membrane or an electrode.    DESCRIPTION OF DRAWING(S) - The figure is a schematic structural view showing components of a fuel cell.    Proton exchange membrane (1)    Fuel cell electrode (2, 3)    Fuel chamber (8)    Fuel cell (21)