The catalytic activity of some carbon-supported electrocatalysts toward the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR) in the presence of ethanol was investigated. It was found that anodes based on PtSn alloys possess a higher catalytic activity for the EOR, compared to other anode catalysts such as Pt, PtRu, and Pt oxide. For example, when tested in a direct ethanol fuel cell, a twofold increase was observed in the current density obtained from a PtSn-Pt membrane electrode assembly (MEA) configuration at 0.4 V, compared to the current density obtained from a PtRu-Pt MEA. Furthermore, it was found that cathode catalysts based on Ru/C exhibit a good catalytic activity for the ORR and a high selectivity for this reaction in the presence of ethanol. The results showed that in the presence of 0.125, 0.25, or 0.5 M ethanol concentrations, a decrease in the onset potential of about 60, 62, and 68 mV emerged, respectively. These values were about ten times lower than those measured for some Pt-based cathode catalysts tested in this study in the presence of 0.125 M EtOH. Accordingly, an ethanol fuel cell based on a PtSn/C anode and a Ru/C cathode showed important current density vs cell voltage characteristics. (c) 2008 The Electrochemical Society.