Pt-Ru nanoparticles supported on high surface area carbon were synthesized by reduction of the precursors with sodium formate, a modification of the reduction method with formic acid developed in this laboratory, which allows the incorporation of higher amounts of Ru. The catalysts were characterized by EDX and XRD. Electrochemical experiments involved cyclic voltammetry, linear sweep voltammetry and current-potential curves for the oxidation of hydrogen and carbon monoxide using an ultrathin layer rotating disc electrode. Levich and Tafel plots were used to examine the mechanism of the reactions. The results were compared with those obtained using a commercial Pt-Ru catalyst. (c) 2006 Elsevier B.V. All rights reserved.