Isotopic tracer diffusion studies have been performed on the perovskite composition La0.2175Pr0.2175Ba0.145Sr0.4Fe0.8Co0.2O3-delta to obtain the diffusion and surface exchange coefficients for oxygen. This material has been identified as a highly active electrocatalytic cathode for intermediate temperature solid oxide fuel cells. The oxygen diffusion coefficients obtained in the 450-650 degrees C temperature range are higher than the ones measured for most of the cathode materials reported in the literature and they agree with those calculated from electrochemical impedance spectroscopy measurements performed on symmetrical cells. (C) 2012 Elsevier B.V. All rights reserved.