This study examines the oxygen adsorption and desorption characteristics of La0.5Sr0.5Co0.8Fe0.2O3-delta (LSCF5582) membranes prepared at sintering temperatures of 1200-1300 degrees C, with the aim of gaining an insight into their performance in the surface reaction limited regime for oxygen separation applications. The findings of this work are then compared with our experimental data on Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF5582) membranes. It is demonstrated that the adsorption rate constants of both membranes are two orders of magnitude greater than their respective oxygen desorption rate constants as the oxygen adsorption occurs in less than 24 s whilst the oxygen desorption takes approximately one hour to reach equilibrium. The activation energy for oxygen adsorption of LSCF5582 reduced to a quarter of its value with increasing the sintering temperature from 1200 degrees C to 1300 degrees C. This is attributed to the oxygen exchange occurring more rapidly along the grain boundaries resulting in a lower activation energy. The LSCF5582 grain sintered at 1200 degrees C is the optimum selection for oxygen separation applications at an operating temperature of 850 degrees C and oxygen partial pressure of 0.21 bar. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.