A novel micro-band electrode (MBE) cell was designed to study the oxygen reduction at the platinum/polymer electrolyte interface at normal to elevated temperatures and under various relative humidities. A mathematic model is used for the design validation and geometric parameters selection. This technique has been applied to the investigation of the O-2 reduction in the Pt/polybenzimidazole (PBI)-phosphoric acid system at elevated temperature and low humidity. A Tafel plot with expanded current density range is obtained, together with the oxygen diffusion coefficient and solubility in phosphoric acid-doped PBI. Both the kinetic parameters and the oxygen transport parameters are comparable to those from the Pt/phosphoric acid system under similar conditions. (C) 2004 Elsevier Ltd. All rights reserved.