TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Material: The electron conductor is made of a carbonaceous material, e.g. graphite or a carbon nanotube. The proton conductor contains a phosphorus-containing compound, a sulfur-containing compound, carboxylic acid, boric acid, and/or inorganic solid-state acid. The proton conducting material is a phosphorus-containing compound, phosphoric acid, ester phosphate, sulfuric acid, ester sulfate, sulfuric acid, tungsten oxide hydroxide, rhenium oxide hydroxide, silicon oxide, tin oxide, zirconia oxide, tungstophosphoric acid, and/or tungstosilicic acid. The mixed conductor supports a noble metal catalyst.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: An electron conductor made of inorganic material obtained by carbonizing an organic material is fixed to a proton conductor made of an inorganic material by a covalent bond, inclusion, or intercalation. It is obtained by carbonizing aliphatic hydrocarbon, aromatic hydrocarbon, and/or derivatives of the aliphatic hydrocarbon and the aromatic hydrocarbon. The electron conductor has consecutive carbon-carbon bonds including a carbon-carbon double bond. It is obtained by carbonizing an organic compound having one of or both of a carbon-carbon double bond and a carbon-carbon triple bond. An organic compound having pi bond is dehydration-condensation polymerized and bound with a compound having movable protons to obtain a precursor having proton conduction.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Material: The electron conductor is made of a carbonaceous material, e.g. graphite or a carbon nanotube. The proton conductor contains a phosphorus-containing compound, a sulfur-containing compound, carboxylic acid, boric acid, and/or inorganic solid-state acid. The proton conducting material is a phosphorus-containing compound, phosphoric acid, ester phosphate, sulfuric acid, ester sulfate, sulfuric acid, tungsten oxide hydroxide, rhenium oxide hydroxide, silicon oxide, tin oxide, zirconia oxide, tungstophosphoric acid, and/or tungstosilicic acid. The mixed conductor supports a noble metal catalyst.    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The electron conductor contains polyacetylene, resorcinol, phenol, phenylphenol, polyaniline, polypyrrole, polythiophene, phenylphosphonic acid, and/or phenylsilane alkoxide. EXAMPLE - Resorcinol (10 g) and formaldehyde (13 ml) were dissolved in water (40 ml), and a solution obtained by hydrolyzing trimethyl phosphate was added to the solution. The solution was subjected to reflux at 100-200degreesC for 4 hours and covalent bond between electron conductor and proton conductor in the solution was promoted. The resultant solution was dehydrated and condensed with sodium carbonate as a catalyst. This gel was dried at 120degreesC, thus obtaining a precursor. The precursor was subjected to a pyrolysis (at 500-1000degreesC) under a nitrogen atmosphere to obtain a mixed conductor. The mixed conductor was ground to powder and caused to support a platinum catalyst. The powder was subjected to hot pressing. The mixed conductor exhibited both proton conduction and electronic conduction at low temperature to 60degreesC.