`We investigated the electrical conductivity and electrochemical properties of hydrous sulfated nano-titania. The conductivity reached 0.1 S cm(-1) at 50 degrees C under a relative humidity of 80%. Diffuse reflectance FT-IR spectra suggest that bidentate sulfate coordination likely forms on the nano-titania surface, which in turn contributes to the electrical conduction. The conductivity depended on relative humidity. Using a hydrogen concentration cell, we found that the electromotive force (EMF) of the nano-titania was almost the same as the theoretical value. These results suggest that the main conduction mechanism is proton conduction on the surface of the titania nanoparticles with the aid of sulfonic acid groups bound to the surface of the oxide. (C) 2010 Elsevier B.V. All rights reserved.