The electrocatalytic oxidation of methanol has been studied on platinum (Pt), glassy carbon and graphite electrodes modified by a thin film of poly(o-phenylenediamine) (PoPD) containing dispersed platinum particles. The results show that poly(o-phenylenediamine) significantly enhances the catalytic efficiency of platinum microparticles for oxidation of methanol in aqueous acid media, especially on a platinum substrate. Dispersion of the platinum particles into a PoPD film increases the catalytic response to a greater degree, which is quite significant in the case of a Pt/PoPD/Pt electrode, The effects of various parameters such as the nature of the electrode substrate, platinum loading, thickness of the polymer film, concentration of methanol, medium temperature, platinum loading procedure, as well as the reproducibility of the electrode response, have also been investigated.