TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Layer: The functional layer is formed on both surfaces of the film. The functional layer is a functional material having a multilayered structure comprising laminate of two or more sheets. The functional material is formed by repeatedly drying the layer, after contacting the film surface with two or more liquids. The functional layer has thickness of 0.1-20 microns. The functional layer is a catalyst layer containing metal which promotes oxidation reaction hydrogen and reduction reaction of oxygen as catalyst. The catalyst layer contains two or more metals.Preferred Metal: The metal is gold, iridium, platinum, rhodium, ruthenium, tungsten, tantalum, niobium, titanium, palladium, bismuth, nickel, copper, iron and/or hafnium.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Solvent: The organic solvent is mixture of good solvent and poor solvent of solid electrolyte. The weight proportion of poor solvent in organic solvent is 10-100%. The good solvent is dimethyl sulfoxide. The poor solvent contains 1-5C alcohol.    TECHNOLOGY FOCUS - POLYMERS - Preferred Compound: The solid electrolyte is a hydrocarbon group polymer, preferably an aromatic polymer having sulfonic acid group. The aromatic polymer is a copolymer containing structural units of formulae (I or II), or unit of formula: -(O-Z-O)-.X = H;Y = SO2;Z = group of formula (a or b);andn/(m+n) = 0.1-0.5. EXAMPLE - Nafion DE2020 (RTM: dispersion solution) (in wt.pts) (100) and perfluorohexane (solvent) (400) were mixed on dry basis, and solid electrolyte dope was produced. The obtained dope was flow-spread from spread die, and a spread film was formed. The film was dried by spraying wind of temperature 30-50degreesC, until the residual solvent amount was set to 30 wt.%. The spread film was torn off, and further dried by spraying 50degreesC dry wind until residual solvent content was 15 wt.%. Cutting removal of damaged portion of both ends of film was carried out. The coating liquid containing VulcanXC72 (RTM: platinum supported carbon) (10), dope (A) (50) and perfluorohexane/methanol solution (40) was applied on anti-support surface at rate of 50 ml/m2, dried at 30-70degreesC, catalyst layer was formed. The resulting film was dried at 50-70degreesC, and solid electrolyte film was obtained. The film had mean value thickness of 51 microns, variation in thickness of plus minus 1.4 microns, residual solvent amount of 0.5 wt.%, and ion electrical conductivity of 0.13-0.14 S/cm. The electrolyte film provided fuel cell having power density of 0.57-0.6 W/cm2.