Graphene oxide (GO) prepared by the modified Hummers method is used as a support in the formation of a Pt/GO nanocomposite electrocatalyst by microwave-polyol synthesis. The effects of microwave reaction times on particle size, dispersion, and electrocatalytic performance of Pt nanoparticles are studied using wide-angle X-ray diffractometery, Raman spectroscopy, transmission electron microscopy and three-electrode electrochemical measurements. The results indicate that Pt nanoparticles nucleation and growth occur, and the particles are uniformly deposited on the GO nanosheets within a short time. The maximum electrochemical active surface area 85.71 m(2) g(-1) for a Pt/GO reaction time of 5 min, is a result of the deposition of a dense dispersion of small Pt particles. The highest methanol oxidation peak current density, I(f) of 0.59 A mg(-1) occurs for a Pt/GO reaction time of 10 mm and is due to the formation of interconnecting Pt particles clusters. This novel Pt/GO nanocomposite electrocatalyst with high electrocatalytic activities has the potential for use as an anode material in fuel cells. (C) 2011 Elsevier B.V. All rights reserved.