Perovskite oxide sorbents offer promise for adsorption-based separation of air to produce an oxygen enriched stream. The oxygen desorption rate however should be further improved. This work studies the oxygen sorption properties of three La1-xSrxCo1-yFeyO3-delta (LSCF) perovskite oxides with and without oxygen vacancy disorder order phase transition. The LSCF with lower iron content [La0.1Sr0.9Co0.9Fe0.1O3-delta (LSCF1991)] shows the highest sorption capacity in 500-800 degrees C. The material with disorder-order phase transition during desorption also exhibits enhanced oxygen desorption rate during the TGA measurement. However,. in the fixed-bed desorption process, no obvious rate enhancement resulting from the disorder order phase transition in oxygen desorption is observed for the LSCF1991 sorbent. The LSCF1991 sample in the fixed-bed quenched at 600 degrees C after, 2 h of desorption shows occurrence of disorder order phase transition for the perovskite sorbentin the fixed-bed environment. The difference in oxygen desorption rate observed between the fixed-bed process and the TGA experiment is due to much higher oxygen-partial pressure in the gas surrounding the sorbent during the fixed-bed oxygen desorption process under which the disorder-order phase transition does not occur until the late stage of oxygen desorption.