A simple, environment-friendly and aqueous-route colloidal-precipitation method is successfully employed to prepare carbon supported platinum nanoparticles with a narrow size distribution. In this method, (NH4)(2)WO4 is used to react with H2PtCl6, which forms the (NH4)(2)PtCl6 and H2WO4 simultaneously. The precipitation of (NH4)(2)PtCl6 and the colloidal of H2WO4 can protect the formation of the Pt nanoparticles. Transmission electron microscopy demonstrates that the Pt nanoparticles with a narrow size distribution are well dispersed on the carbon support. More importantly, the size of the Pt nanoparticles can be simply controlled by tuning the concentration of (NH4)(2)WO4 and the Pt nanoparticles prepared in the 0.5 mmol L-1 (NH4)(2)WO4 exhibit the smallest size of ca. 3 nm. Further, cyclic voltammetric and chronoamperometric experiments show that the prepared Pt/C catalyst exhibited excellent catalytic activity and stability compared with the Pt/C prepared by impregnation method and the state-of-the-art commercial Pt/C. For example, the peak current and the stable current at 3600 s of the Pt/C catalyst prepared with the 0.5 mmol L-1 (NH4)(2)WO4 is about 1.24 and 1.78 times of the commercial Pt/C. Therefore, the as-proposed colloidal-precipitation method exhibits a potential application in preparing highly dispersive and electroactive Pt/C catalysts for direct methanol fuel cells. (C) 2012 Elsevier B.V. All rights reserved.