TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The electro-catalyst composition additionally comprises several catalytically active particles of a transition metal, nucleated around the covalently bonded transition metal atoms; and several catalytically active particles of a transition metal physically dispersed in the polymer. The composition forms a thin-film electrode comprising pores that are interconnected. The electro-catalyst composition additionally comprises nano catalyst particle-bearing conductive particles dispersed in the polymer, where the conductive particles are selected from carbon black, nanometer-thickness graphite platelets, carbon nano-fibers, graphitic nano-fibers, carbon nanotubes and/or carbon nano-scrolls. The catalytically active particles of a transition metal have an average dimension smaller than 2 nanometers. The catalytically active particles of a transition metal physically dispersed in the polymer have an average dimension smaller than 2 nanometers. Preferred Components: The transition metal atoms include atoms selected from platinum, iridium, osmium, rhenium, ruthenium, rhodium, palladium, iron, cobalt, nickel, chromium, manganese, copper and/or vanadium. The transition metal atoms include non-platinum atoms selected from iron, cobalt, nickel, chromium, manganese, copper and vanadium, and the catalytically active particles of a transition metal have an average dimension smaller than 1.5 (preferably smaller than 1) nm.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The polymer is selected from sulfonated polyaniline, sulfonated polypyrrole, sulfonated polythiophene, sulfonated polyfuran, sulfonated bi-cyclic polymer and/or their derivatives. When the polymer is sulfonated polyaniline, sulfonated polypyrrole, sulfonated polythiophene or sulfonated polyfuran, then the transition metal is platinum, iridium, palladium, cobalt, nickel, iron, manganese, copper and/or vanadium. The polymer comprises a mixture of an electron-conducting polymer and a proton-conducting polymer. The proton-conducting polymer is selected from poly(perfluoro sulfonic acid), sulfonated polytetrafluoroethylene, sulfonated perfluoroalkoxy derivatives of polytetra-fluoroethylene, sulfonated polysulfone, sulfonated poly(ether ketone), sulfonated poly (ether ether ketone), sulfonated polystyrene, sulfonated polyimide, sulfonated styrene-butadiene copolymers, sulfonated poly chloro-trifluoroethylene, sulfonated perfluoroethylene-propylene copolymer, sulfonated ethylene-chlorotrifluoroethylene copolymer, sulfonated polyvinylidenefluoride, sulfonated copolymers of polyvinylidenefluoride with hexafluoropropene and tetrafluoroethylene, sulfonated copolymers of ethylene and tetrafluoroethylene, polybenzimidazole, and chemical derivatives, copolymers, and their blends. The electron-conducting polymer is selected from polyaniline, polypyrrole, polythiophene, polyfuran, bi-cyclic polymers, and/or their derivatives. EXAMPLE - No suitable example given.