Two and 4 wt% Pd/C and Pd/Vulcan catalysts were synthesized by the impregnation method, from Pd (II) acetyl acetonate (aldrich, 99%) precursor dissolved in acetone. The catalysts and the supporting materials (carbon and Vulcan) were characterized by X-ray diffraction, temperature programmed reduction and atomic absorption spectroscopy. Pd/C and Pd/Vulcan catalysts were electrochemically characterized by cyclic as well as linear voltammetry. These catalysts were finally tested in the cathode of a proton exchange membrane fuel cell. The results of the electrochemical characterization and the fuel cell test indicated that Pd supported on vulcan performed better than Pd supported on C as the cathode. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.