Electrochemical techniques such as ac impedance analysis and cyclic voltammetry have been employed to investigate the effect of ionomer content in the anode on the performance of direct methanol fuel cells. Two different types of catalysts, black and supported catalysts, were used to compare the effect of catalyst morphology on the electrochemical properties of the electrodes. Electrochemical surface areas that were measured with complete cells using cyclic voltammetry increased with increasing ionomer content for the MEAs with supported catalyst, but varied with a maximum value for the MEAs with black catalyst. Charge transfer resistance in the anode that was measured using an impedance analysis also increased with an increase in ionomer content, but it showed a minimum value at an ionomer content which was dependent on the type of catalysts used in the MEAs. (C) 2004 Elsevier Ltd. All rights reserved.