A Pt catalyst film with dendritic microcrystalline structure has been prepared by reducing PtO2 deposited by reactive sputtering. It is to be employed as the cathode catalyst of a polymer electrolyte fuel cell (PEFC). Despite using no support material, this dendritic Pt film exhibits a very low density of 3.3 g cm(-3). When applying the dendritic Pt as the cathode catalyst layer for a single fuel cell, the dendritic Pt provided higher performance, larger electrochemical surface area (ECA) and improved diffusion characteristics compared to a conventional sputtered Pt film. The activity based on unit ECA of the dendritic Pt was higher than that of Pt/C. (C) 2008 Elsevier B.V. All rights reserved.