Three different electrodes containing polyaniline (PAN!) and platinum (Pt) nanoparticles were fabricated. Polyaniline was coated onto TGPO60-T by carrying out the electro-polymerization of aniline and trifluoromethane sulfonic acid as the proton-conductive monomer, and platinum was electroreduced onto the carbon paper based electrodes (with or without polyaniline) that are used in direct methanol fuel cells (DMFCs). The efficiencies of these electrodes in methanol oxidation were examined and their electrochemical properties were investigated with cyclic voltammetry, chronoamperometry, linear sweep voltammetry, and electrochemical impedance spectroscopy. The surface morphologies of the electrodes were characterized by using scanning electron microscopy. The electro-oxidation reaction on the Pt-PANI/carbon paper catalyst with a thick layer of polyaniline has a much lower activation energy than on the Pt/carbon paper catalyst and on the Pt-PANI/carbon paper catalyst with a thin layer of polyaniline. Our results also show that the electrode with a thick polyaniline layer is more efficient than the electrodes with a thin polyaniline layer or without polyaniline. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.