The electrochemical properties of La0.6Ba0.4CoO3-delta (LBC) and La0.6Sr0.4CoO3-delta (LSC) dense thin film model electrodes, deposited by pulsed laser deposition at 600 degrees C on yttria-stabilized zirconia (100) electrolytes, were investigated by electrochemical impedance spectroscopy (EIS) at 450-600 degrees C and 10(-4) to 1 bar pO(2). This comparative study reveals the influence of the A-site dopant size on the catalytic activity for the oxygen exchange, chemical capacitance and electronic conductivity. For both thin films the overall oxygen reduction is still limited by the oxygen surface exchange, although an extraordinarily high activity for the oxygen reduction reaction (ORR) was measured (LBC similar to 0.18 Omega cm(2)/LSC similar to 0.6 Omega cm(2) at 604 degrees C and 0.21 bar pO(2)). Moreover, LBC exhibits a rather low activation energy for the ORR (1.19 +/- 0.11 eV) together with a high electronic conductivity (839 S . cm(-1) at similar to 442 degrees C). Based on these excellent electrochemical properties, LBC may also be a highly promising material for porous cathodes in intermediate temperature (400-600 degrees C) solid oxide fuel cells. (C) The Author(s) 2016. Published by ECS. All rights reserved.