Anhydrous proton conducting material for polymer electrolyte membrane fuel cell (PEFC) was prepared by the mixing of zwitterionic-type molecular solid 3-pyridinesulfonic acid (PS) and organic acid methylenediphosphonic acid (MP). As a result, PS molecule, which has sulfonic acid and pyridine group in its structure, showed the proton conductivity of 4 x 10(-5) S cm(-1) at 160 degreesC under anhydrous condition. Surprisingly, by the mixing of MP to PS material, the PS-MP composite material exhibited a conductivity of 2 X 10(-3) S cm(-1). Moreover, the conductivity of PS-MP composite material did not decrease under the heating at 160 degreesC for 50 h. (C) 2004 Elsevier B.V. All rights reserved.