TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The proton conductive material contains sulfate as base material. Calcium, sulfur and hydrogen are present in the conductive material in the form of (in wt.%) calcium oxide (10-45), sulfur trioxide (15-60) and water (5-55). The conductive material further contains phosphorus in the form of phosphorus pentaoxide (0.1-50), and calcium sulfate, preferably calcium sulfate dihydride (40 or more). The proton conductive material is formed by curing raw material containing calcium sulfate and water, preferably an aqueous solution containing calcium sulfate hemihydrate, and phosphoric acid and/or phosphate. A movable hydrogen ion is introduced, or an aqueous solution containing phosphoric acid and/or phosphate is impregnated into the cured material having plaster as base material.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The proton conductive material contains sulfate as base material. Calcium, sulfur and hydrogen are present in the conductive material in the form of (in wt.%) calcium oxide (10-45), sulfur trioxide (15-60) and water (5-55). The conductive material further contains phosphorus in the form of phosphorus pentaoxide (0.1-50), and calcium sulfate, preferably calcium sulfate dihydride (40 or more). The proton conductive material is formed by curing raw material containing calcium sulfate and water, preferably an aqueous solution containing calcium sulfate hemihydrate, and phosphoric acid and/or phosphate. A movable hydrogen ion is introduced, or an aqueous solution containing phosphoric acid and/or phosphate is impregnated into the cured material having plaster as base material. EXAMPLE - A mixture of calcium sulfate hemihydrate and water in the weight ratio of 50:50, was molded into a disk-shaped compact. The compact was cured by natural seasoning to form proton conductive material having proton conductivity of 4x10-5 S/cm at room temperature and containing calcium oxide (in wt.%) (19.3), sulfur trioxide (27.6) and water (53.1).