A microwave-assisted microemulsion synthesis of carbon supported Pt-WO3 nanoparticles is presented. Amorphous WO3 nanoparticles of 1.0 nm in size were first deposited onto carbon from an alkaline tungstate containing microemulsion via mixing with an acid containing microemulsion under controlled microwave exposure. Platinum was subsequently deposited onto the carbon supported WO3 nanoparticles by reducing H2PtCl6 in a microemulsion under controlled microwave exposure forming nanoparticles with an average size of 2.5 nm. This method produced a homogeneous distribution of nanoparticles on the carbon support with a uniform Pt:W ratio. The Pt:W can be well controlled by varying the metal precursors' Pt:W ratio. Hydrogen adsorption, CO-stripping and Cu-UPD stripping method were used to estimate the electrochemical surface area of Pt in the Pt-WO3 mixed catalyst system. Cyclic voltammetry and chronopotentiometry experiments demonstrate that a 1:1 ratio of Pt:W has the highest electrocatalytic activity based on Pt mass for methanol oxidation in sulfuric acid. The enhanced electrocatalytic activity is attributed to both physical and chemical influence of the WO3 component. (C) 2012 Elsevier Ltd. All rights reserved.