Our recent research on electrocatalysts for polymer electrolyte fuel cells has been reviewed. An electrocatalytic activity of Pt for O₂ reduction was enhanced significantly by alloying Pt with Fe, Co and Ni. Alloys of Pt-Fe, Pt-Co and Pt-Mo were found to exhibit excellent CO-tolerance at H₂ oxidation. From various analyses, it was found that the surfaces of all the alloys used are composed of a thin Pt layer with an electronic structure different from that of pure Pt, indicating an increased in 5d vacancy of Pt. For methanol oxidation reaction (MOR), we successfully evaluated the activities of Pt-Ru alloy and Pt electrodes in a wide temperature range from 20 to 120^oC by using a thin-layer flow cell under pressurized operation. Adsorbed water molecules that promote the MOR at Pt-Ru alloy electrode were clearly detected by in situ FTIR spectroscopy, which directly supports the “bi-functional mechanism” for the MOR.