The temperature dependence of the oxygen reduction reaction (orr) activity at a platinum electrode in 0.1 M HClO4 electrolyte solution was investigated with a channel flow double electrode at 20-90 degreesC. We demonstrate that an apparent rate constant (k(app)) for the orr can be evaluated from the hydrodynamic voltammograms by correcting the oxygen concentration in the electrolyte solution. The apparent activation energy for the k(app) was found to be 38 kJ/mol at -0.525 V vs. E-0 (0.760 V vs. RHE at 30 degreesC). Production of H2O2 was not detected at potentials more positive than 0.3 V in the temperature region examined. One capacitive semicircle was observed in electrochemical impedance spectroscopy for the orr, suggesting the fast complete reduction of intermediates to H2O following the rate determining step of the first electron-transfer. (C) 2004 Elsevier B.V. All rights reserved.