TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Component: Each electrocatalyst layer comprises catalyst layer and interfacial composite layer. The catalyst layer comprises catalyst material and electrolyte medium. It forms a homogeneous, continuous structure with the interfacial composite layer. The electrolyte medium comprises electrolytic material(s).Preferred Property: The catalytic material comprises metal or metal alloy having an average particle size of 1-100 nm. The catalyst layer is characterized by a catalytic surface area of 1-200 (preferably 10-100) m2/g, and an electrical resistance of 0.1-1000 (preferably 0.1-100) OMEGA measured over a distance of 1 mm. The interfacial composite layer is characterized by a catalytic surface area of 1-200 (preferably 10-100) m2/g, and an electrical resistance of 0.1-10000 (preferably 1-100) OMEGA measured over a distance of 1 mm.Preferred Method: The electrocatalyst layer is formed by flowing an electrocatalyst precursor solution through the bore side of the fuel cell precursor, flowing a reducing medium through the shell side of the cell precursor, and adjusting processing conditions to diffuse the reducing medium through membrane separator to react with the electrocatalyst precursor solution. A first layer of electrolyte medium is dried and heat-treated at 25-15degreesC    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The solid electrolyte material comprises an ion-exchange polymer from perfluorocarbon-sulfonic-acid-based polymers, polysulfone-based polymers, perfluorocarboxylic-acid-based polymers, styrene-vinyl-benzene-sulfonic-acid-based polymers, or styrene-butadiene-based polymers.    TECHNOLOGY FOCUS - METALLURGY - Preferred Component: The catalytic material comprises metal from platinum, gold, ruthenium, iridium, palladium, rhodium, nickel, iron, molybdenum, tungsten, niobium, or their alloy. It preferably comprises platinum or platinum alloy. The metal can be platinum-ruthenium alloy, platinum-ruthenium-iron alloy, platinum-molybdenum alloy, platinum-chromium alloy, platinum-tin alloy, or platinum-nickel alloy. The electrocatalyst layer precursor solution comprises platinum, gold, ruthenium, iridium, palladium, rhodium, nickel, iron, molybdenum, tungsten, or niobium. It may comprise noble metal salt from H2PtCl6, K2PtCl4, RuCl3.xH2O, K2RuCl5, or K2RuCl5(NO). It comprises Pt(NH3)4Cl2 or sodium ions.Preferred Composition: The hollow fibrous membrane separator comprises metal catalyst(s) from platinum, gold, ruthenium, iridium, palladium, rhodium, and their alloys at a concentration of 0.1-80 wt.% of the solid electrolyte material. It also includes metal oxide(s) from silica, titania, alumina, zirconia, or stannic oxide, at a concentration of 0.1-50 wt.% of the solid electrolyte material. The electrolyte composition contains 0.1-10 wt.% electrolyte medium.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The electrocatalyst precursor solution comprises organic solvent(s) including 1-8C alcohols. The reducing medium comprises reducing agent(s) from sodium borohydride, hydrazine, hydrogen, sodium thiosulfate, potassium thiosulfate, formaldehyde, formic acid, hypophosphites, amine boranes, hydroxylamine, acetaldehyde, hydroquinone, propionaldehyde, methyl magnesium chloride, lithium aluminum hydride, thiourea, or thioacetamide.