Proton conductive inorganic-organic hybrid membranes with acid-base pairs have been prepared from 3-aminopropyltriethoxysilane and phosphoric acid by the sol-gel method. The self-standing membranes obtained are represented as poly(3-aminopropylsilsesquioxane)-H3PO4 (PAPS-H3PO4) membranes. Infrared absorption spectra of the PAPS-H3PO4 films showed that amino groups of PAPS were protonated by phosphoric acid, indicating the formation of acid-base pairs. X-ray diffraction patterns of the PAPS-H3PO4 membranes showed diffraction peaks attributed to hexagonal structure, which is probably formed by stacking of rodlike polysiloxane with the acid-base pairs extruded outside. The conductivities of the PAPS-H3PO4 membranes with a molar ratio Of H3PO4/APTES = 1.0 was 4 x 10(-4) S cm(-1) at 150 degrees C under dry condition. (c) 2008 Elsevier B.V. All rights reserved.