The structure, chemistry and morphology of commercially available carbon-supported and unsupported Pt-Ru catalysts are investigated by X-ray diffraction, energy-dispersive analysis by X-rays and electron microscopy. The catalytic activities of these materials towards electrooxidation of methanol in solid-polymer-electrolyte direct methanol fuel cells have been investigated at 90 degrees C and 130 degrees C with varying amounts of Nafion(R) ionomer in the catalytic layer. The unsupported Pt-Ru catalyst exhibits higher performance with lower activation-control and mass-polarization losses in relation to the carbon-supported catalyst.