Durability of electrocatalysts under severe operational conditions of polymer electrolyte fuel cells (PEFCs) is one of the most important technological issues to be improved. Alternative electrocatalyst support materials are desired, the use of which may solve problems such as oxidation-induced carbon support corrosion. One interesting solution is to use conductive oxide-based catalyst support. We focus our attention to SnO 2, known as an oxide semiconductor with a high electronic conductivity, as a possible electrocatalyst support material. Nanostracture, electrochemical properties and durability of carbon-free electrocatalysts, Pt/SnO2, Pt/Nb-SnO2, Pt/Sb-SnO2, and Pt/Al-SnO2, are investigated. Nano-carbon support materials are also studied as an another option of electrocatalyst support design. Distribution of Pt nanoparticles on such carbon support materials is characterized. Pt electrocatalysts with a diameter of a few nm could be prepared, supported on carbon nanofibers with different structures (including herringbone-type fibers, platelet-type fibers, and highly-conductive vapor-grown fibers) and carbon nanotubes. Technical merits and remaining issues in alternative electrocatalyst support materials selection are discussed.