A comparative study of the use of supported and unsupported catalysts for direct methanol fuel cells has been performed. The effect of catalyst loading, fuel concentration and temperature dependence on the anode, cathode and full fuel cell performance was determined in a fuel cell equipped with a reversible hydrogen reference electrode. Although the measured specific activities of supported catalysts were as much as 3-fold greater than the unsupported catalysts, membrane electrode assemblies prepared with supported catalysts showed no improvement with loadings above 0.5 mg/cm(2). Fuel cells utilizing 0.46 mg/cm(2) supported catalyst electrodes performed as well as unsupported catalyst electrodes with 2 mg/cm(2). The temperature dependence and methanol concentration dependence studies both suggest increased methanol permeation through the thinner supported catalyst layers relative to the unsupported catalyst layers.