NOVELTY - A fuel cell electrocatalyst for use in oxidation or reduction reactions, comprises platinum, rhodium, molybdenum, and nickel and/or iron.    USE - The invention is used for oxidation or reduction reactions in fuel cell, such as for the electrochemical conversion of hydrogen-containing fuel and oxygen to reaction products and electricity in fuel cell (claimed). This 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 systems; mobile communications 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.    ADVANTAGE - The invention has improved corrosion resistance and/or improved activity compared to platinum.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a supported electrocatalyst particle for use in electrochemical reactor devices, comprising an electrocatalyst and electrically conductive support particle upon which the electrocatalyst is dispersed;    (2) a fuel cell electrode comprising electrocatalyst particles and electrode substrate upon which the electrocatalyst particles are deposited;    (3) a fuel cell (21) comprising an anode (2), a cathode (3), a proton exchange membrane between the anode and the cathode, and an electrocatalyst; and    (4) a method for the electrochemical conversion of hydrogen-containing fuel (F) and oxygen (O) to reaction products and electricity in a fuel cell, comprising contacting the fuel or the oxygen and the electrocatalyst.    DESCRIPTION OF DRAWING(S) - The figure is a schematic structural view showing members of a fuel cell.    Anode (2)    Cathode (3)    Current collectors (4, 5)    Sealants (6, 7)    Fuel cell (21)    Hydrogen-containing fuel (F)    Oxygen (O)