TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: A preferred resin composition contains as the proton conductive substituent, a group selected from phenolic hydroxyl group, sulphonate group, carboxylate group and phosphate group. A preferred resin composition comprises:(A) a repeating structural unit obtained by polycondensation of a polyfunctional component having three or more amino groups and a tetracarboxylic acid dianhydride;(B) a repeating structural unit obtained by polycondensation of a diamine having a proton conductive substituent and a tetracarboxylic acid dianhydride; and(C) A preferred resin composition further comprises a repeating structural unit obtained by polycondensation of a diamine having no proton conductive substituent and a tetracarboxylic acid dianhydride. SPECIFIC COMPOUNDS - The tetracarboxylic acid dianhydride is selected from 1,4,5,8-naphthalene tetracarboxylic acid dianhydride, and 3,3', 4,4'-biphenyl tetracarboxylic acid dianhydride. The diamine having proton conductive substituent is selected from 2,2'-benzidinesulfonic acid, 2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid and 3,3'-dimethyl-4,4'-diaminobiphenyl-6,6'-disulfonic acid. The diamine containing no proton conductive substituent is 9,9-bis(4-aminophenyl)fluorine. The polyfunctional component having three or more amino groups is 3,3'-diaminobenzidine.    EXAMPLE - 4.30 g of 2,2'-benzidinesulfonic acid, 105 g of phenol, 70 g of p-chlorophenol and 15.18 g of triethyl amine were added to a flask and stirred for 0.5 hours under nitrogen gas flow. 6.70 g of N-methyl-2-pyrolidone, 4.27 g of 9,9-bis(4-aminophenyl)fluorine, and 0.05 g of 3,3'-diaminobenzidine were added in one portion then 50 g of toluene was added and stirred under nitrogen flow at 150 degreesC for 5 hours. The generating water was removed by azeotropy with toluene. The toluene was removed under reflux and the reactant was cooled to room temperature. 26.1 g of HCl and 1L of methanol were mixed vigorously and the reactant was added thereto dropwise and the resulting precipitate was washed with methanol, dried under reduced pressure at 120 degreesC for 3 hours to give the proton conductive polyimide resin composition.