An electrochemical method for the Pt nanoparticles deposition on porous and high Surface carbon substrates (carbon black and carbon nanotubes), as an alternative way to prepare gas diffusion electrodes for polymer electrolyte fuel cells (PEFCs), is herein described. Pt nanoparticles well distributed and localized on the electrode Surface were obtained by using an electric field. The electro-catalysts Were prepared by single and multiple pulse galvanostatic polarizations in 1 M sulphuric acid + 5 mM exachloroplatinic acid solution. Chemical analysis, cyclic voltammetry and field emission gun scanning electron Microscopy were used to determine the electrochemical features of Pt deposits and the influence of electro-deposition method on their nano-morphology. Electro-catalytic performances were Studied by investigating the methanol oxidation reaction and the results are presented ill form Of Surface specific activity and mass specific activity to take into account the electrochemical real surface and Pt loading. A comparison with commercial E-TEK Pt/C catalysts, prepared by traditional chemical reduction and heat treatment in hydrogen, shows that the electrodeposited Catalyst presents higher activity at lower Pt loading. (C) 2008 Elsevier B.V. All rights reserved.