The activities of three 30 wt.% PtRu/C catalysts of the same nominal composition (Pt:Ru, 1:1 a/o) were investigated with regard to methanol oxidation. The catalysts were synthesized by Bonnemann's colloidal precursor method using different metal salt precursors and reducing agents. The catalysts were characterized ex situ by energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) and in situ CO stripping and cyclic voltammetry. The activity towards methanol electro-oxidation was checked in steady-state experiments at 22 and 60 degrees C. The experimental rate data can be described well by a kinetic model, which includes methanol adsorption on the Pt-sites, formation of C-containing adsorbed species, OHM, formation on the Ru sites and heterogeneous surface reaction between C-adsorbate and OHads. The kinetic model parameters were identified from the experimental data and were used to explain the differences in catalytic activity. (c) 2006 Elsevier Ltd. All rights reserved.