Carbon nanotube (CNT)-supported platinum modified with HxMoO3 (Pt-HxMoO3/CNT) was prepared and used as an electrocatalyst for methanol oxidation. In the preparation of this electrocatalyst, a platinum precursor was loaded on CNTs and reduced by sodium borohydride in ethylene glycol, resulting in CNT-supported platinum without modification (Pt/CNT), and then the Pt/CNT was modified with HxMoO3 that was formed by hydrolysis and subsequent reduction of ammonium molybdate. The surface morphology, structure and composition of Pt-HxMoO3/CNT and Pt/CNT as well as their activity toward methanol oxidation were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive spectrometry (EDS), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), chronoamperometry (CA), chronopentiometry, (CP), and electrochemical impedance spectroscopy (EIS). The results, obtained from TEM, XRD, EDS, and FTIR, indicate that the platinum loaded on CNTs has a face-centered cubic structure with particle sizes of 2-5 nm, and the modification of HxMoO3 on platinum with an atom ratio of Pt:Mo = 2:1 has little effect on the particle size, distribution and structure of the platinum. The results, obtained from CV, CA, CP, and EIS, show that the Pt-HxMoO3/CNT exhibits higher electrocatalytic activity toward methanol oxidation and better carbon monoxide tolerance than Pt/CNT. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.