A non-platinum cathode electrocatalyst must have the stability and catalytic activity for the oxygen reduction reaction (ORR) in order to be used in polymer electrolyte fuel cells (PEFCs). Titanium oxide catalysts as the non-platinum catalyst were prepared by the heat treatment of titanium sheets in the temperature range from 600 to 1000 degrees C. The prepared catalysts were chemically and electrochemically stable in 0.1 mol dm(-3) H2SO4. The titanium oxide catalysts showed different catalytic activities for the ORR. The ORR of the catalysts heat-treated at around 900 degrees C occurred at the potential of about 0.65 V versus RHE. It is considered that the deference in the catalytic activity for the ORR of the heat-treated titanium oxide catalysts was due to the fact that the heat-treatment condition changed the material property of the catalyst surface. In particular, it was found that the catalytic activity for the ORR of the Ti oxide catalysts increased with the increase in the specific crystalline structure, such as the TiO2 (rutile) (110) plane and the work function. It is considered that a surface state change, such as the crystalline structure and work function, might affect the catalytic activity for the ORR. (c) 2006 Published by Elsevier Ltd.