The effect of metal cations in solution on the oxidation of methanol on the electrode surface of platinum is a neglected aspect to direct methanol fuel cell (DMFC). In this paper, a smooth platinum electrode absorbing metal cations as the working electrode was applied to investigate the methanol oxidation with the cyclic voltammetry (CV) in 1.0 mol L-1 H2SO4. From the analysis of experiment, it is found that the cations, Li+, Ce4+, Mn2+, Ni2+, Cu2+, have some negative effect on the catalytic oxidation of methanol on the surface of platinum. The degree of the effect from different cations was analyzed. (c) 2006 Published by Elsevier Ltd.