The composite electrodes were prepared by electrochemical deposition of platinum (Pt) nanoparticles onto the surface of tin oxide (SnO2) nanowires directly grown on the carbon fibers of a carbon paper. This is the first report of an electrode design using Pt catalyst supported on a SnO2 nanowire-based electrode. In the comparison to a standard Pt/C electrode, the nanowire-based electrode exhibited higher electrocatalytic activity both for oxygen reduction reaction and methanol oxidation reaction. The results imply that nanowire-based composite electrodes are excellent potential candidates for application in proton exchange membrane and direct methanol fuel cells.