Platinum (Pt) nanoparticles were successfully synthesized on tungsten oxide (WO3) thin films by electroless process without any further post-treatment. The prepared Pt nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and field-emission scanning electron microscopy. Gas sensors based on the Pt-WO3 films were found to provide repeatable and significant responses to ppm-level H-2. The size of Pt nanoparticles increases with the deposition time and has improved the sensing characteristics of the sensors. The work in this paper paves a facile way to the fabrication of Pt nanoparticles on metal oxide surface at a low temperature (68 degrees C). Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.