The perovskite material La0.6Sr0.4Co0.2Fe0.8O3 (LSCF-6428) has been considered as both the anode and cathode in solid oxide fuel cells (SOFCs) operating at intermediate temperatures (550-700 degrees C). Solid electrolyte coulometry (SEC) has been used to measure the oxygen non-stoichiometry as a function of temperature and ambient oxygen partial pressure, thus enabling kinetic data relating to oxygen transport in cathodes to be correlated with the material oxygen vacancy concentration. The catalytic activity towards methane oxidation, and susceptibility to deactivation through carbon deposition have both been investigated by temperature programmed methods, and compared with data for the conventional Ni/YSZ anode material. (C)2000 Elsevier Science B.V. All rights reserved.