Platinum-tungsten trioxide nanocomposite electrocatalysts on carbon black support (Pt-WO3/C) are synthesized and their electrocatalytic performances toward methanol oxidation reaction (MOR) are investigated in this study. Tungsten trioxide, which derived from the hydrolysis of tungsten hexachloride (WCl6) in dimethylformamide (DMF) solution, is firstly deposited onto pristine or NaOH-treated Vulcan XC-72 carbon black (C or C-s) support to obtain tungsten trioxide/carbon black (WO3/C or WO3/C-s) nanocomposites, and then Pt nanoparticles are decorated onto these nanocomposites by polyol method to obtain PtWO3/C or Pt-WO3/C-s electrocatalysts. XRD and TEM characterizations are performed to examine the WO3 structures and the size distributions of the Pt nanoparticles. The effects of WO3 loading, annealing temperature and the NaOH-treatment of carbon black support on MOR mass activity and CO-tolerance ability of the electrocatalysts are investigated. The electrocatalyst (PtW(0.08)C(s)200) with the WO3/C-s nanocomposite derived from a DMF solution containing 0.08 M WC16, using NaOH-treated XC-72 carbon black as the support and annealed at 200 degrees C, achieves the highest MOR activity among all the electrocatalysts synthesized in this study. The MOR performances of PtW(0.08)C(s)200 is superior to that of the commercial ETEK Pt(20 wt%)/C and E-TEK PtRu(20 wt%)/C electrocatalysts under the same test conditions. (C) 2015 Elsevier Ltd. All rights reserved.