Inorganic-organic hybrid proton exchange membranes were prepared via sol-gel reaction of N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (AAS) in a sulfuric or phosphoric acid aqueous solution. The chemical structures of these membranes are characterized by means of Fourier transform infrared (FTIR) and Si-29 cross polarization nuclear magnetic resonance (Si-29 CP NMR). Those acid-doped membranes were stable at temperatures up to about 300 degrees C and showed varied conductivities at different temperature ranges. Optical Microscopy and Scan Electron Microscopy (SEM) analysis revealed that the introduction of H2SO4 led to the generation of nanoparticles in situ. Atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDS) results indicated that these nanoparticles were wrapped by the soft organic side chains. Root-mean-square (RMS) roughness measured by AFM demonstrated that lower water addition during synthesis led to rougher surface and higher conductivity of H2SO4-doped membrane, while the surface of H3PO4-doped membrane remained smooth and clean, and the conductivity did not show a significant change by varying water additions. All those results demonstrated that the higher conductivity of the H2SO4-doped membrane achieved contributed not only to the dissociation of the counter anion but also the morphology of the membrane. Finally, we proposed a potential mechanism for the proton conduction in such acid-doped membranes. This mechanism could possibly provide a method to construct effective proton channels in the cross-linked anhydrous proton exchange membranes. (C) 2010 Elsevier By. All rights reserved.