PtRu/C nanocatalysts with different size were prepared simply by adjusting the pH Of beta-D-glucose solution. Herein, beta-D-glucose acts as a reducing agent as well as a capping agent. Transmission electron microscopy revealed that the well dispersed PtRu particles (12.7, 5.6, and 2.3 nm) were obtained at pH 8.5, 10.5, and 12.5, respectively. X-ray diffraction analysis indicated that the PtRu/C catalysts have different structures synthesized at different pH values. Only at pH 12.5, small amount of PtRu alloy was formed. X-ray photoelectron spectroscopy measurements showed that a large amount of Pt and Ru were present in metallic states. Both cyclic voltammetry and chronoamperometric results demonstrated that the PtRu/C catalyst prepared from the solution at pH 12.5 exhibited better performances for methanol electro-oxidation than the other samples. (c) 2006 Elsevier B.V. All rights reserved.