NOVELTY - A fuel cell electro-catalyst composition comprises a proton- and electron-conducting polymer having at least one heteroatom per backbone monomer unit and several of neutral transition metal atoms covalently bonded to at least a portion of the heteroatoms. The polymer has an electronic conductivity no less than 10-4 S/cm and a proton conductivity no less than 10-5 S/cm.    USE - In a fuel cell electrode, a fuel cell membrane-electrode assembly, an electro-catalyst-coated proton exchange membrane and a fuel cell (claimed).    ADVANTAGE - The incorporation electro-catalyst composition in a fuel cell electrode, catalyst-coated membrane, or membrane electrode assembly leads to much improved fuel cell performance with much reduced Ohmic loss, higher catalyst utilization efficiency, and higher cell output voltage (given the same desired operating current density). The electro-catalyst composition features a much more effective utilization of the catalyst, particularly through the optimization of electron and ion transfer rates, a significant reduction in the nano catalyst particle size, and an optimal dispersion of catalyst particles in three dimensions. The resulting electrode effectively establishes proton-conducting paths, electron-conducting paths, and fuel/oxidant transport paths that enable the same amount of electro-catalyst to induce a higher rate of electrochemical conversion in a fuel cell resulting in significantly improved performance as compared to all of the prior art electro-catalysts.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a fuel cell electrode comprising a gas diffusion layer as a catalyst-supporting layer, where the gas diffusion layer is coated with or impregnated by the electro-catalyst composition;    (2) a fuel cell membrane-electrode assembly comprising a proton-conducting electrolyte layer, a first thin layer of the electro-catalyst composition attached to one surface of the electrolyte layer, a second thin layer of the electro-catalyst composition attached to an opposing surface of the electrolyte layer, a first gas diffusion layer attached to or bonded with the first thin layer of electro-catalyst composition, and a second gas diffusion layer attached to or bonded with the second thin layer of electro-catalyst composition;    (3) an electro-catalyst-coated proton exchange membrane comprising the electro-catalyst composition that is coated on a surface or two opposing surfaces of the membrane; and    (4) a fuel cell comprising either the electro-catalyst composition which is bonded between a gas diffusion layer and a proton exchange membrane; or a proton-conducting electrolyte layer sandwiched between an anode and a cathode, where the anode and/or cathode comprises the electro-catalyst composition; or the membrane electrode assembly, a first separator or bipolar plate connected to the first gas diffusion layer, and a second separator or bipolar plate connected to the second gas diffusion layer.