Ceria (CeO2)-modified PtRu/C catalysts with different compositions of Ru and CeO2, viz. PtRu0.9(CeO2)(0.1)/C, PtRu0.7(CeO2)(0.3)/C and PtRu0.5(CeO2)(0.5)/C and unmodified PtRu/C catalyst were synthesized by the sodium borohydride reduction method. Transmission electron microscopic results indicated that the lower concentrated CeO2-modified PtRu/C catalysts had almost a similar morphological structure (well-dispersed particles with size around 2.3-2.5 nm) with that of the unmodified PtRu/C catalyst. X-ray diffraction and X-ray photoelectron spectroscopy analyses indicated the formation of PtRu alloy and presence of CeO2 in an amorphous form with a mixed oxidation states (Ce3+-Ce4+). Electro-catalytic activity of these catalysts for methanol oxidation was investigated by linear sweep voltammetry and chronoamperometry and it was found that the PtRu0.7(CeO2)(0.3)/C catalyst yielded the higher methanol oxidation current than did the unmodified PtRu/C catalysts. (c) 2005 Elsevier B.V. All rights reserved.