PtRu catalysts were prepared by electrochemical deposition on C-Nafion supports sprayed on stainless steel current collectors. The effect of the electrochemically accessible surface area of the C-Nafion supports, of the Pt to C and Pt to Nafion mass ratio and of the electrodeposition conditions on catalytic activity of the PtRu/C-Nafion catalysts for methanol oxidation in direct methanol fuel cells (DMFC) was investigated. Our results demonstrate that optimized PtRu/C-Nafion catalysts display catalytic activity significantly higher than that of a commercial system tested in the same conditions. (C) 2004 The Electrochemical Society.