A polycarbonate/(N,N’-dialicylidene ethylene diamine) cobalt(II) (cosalen) complexed membrane was prepared by introducing oxygen carrier (cosalen) into polycarbonate for gas separation. With increasing amount of oxygen carrier in the membranes, the selectivity of O-2/N-2 increased and the permeabilities of both O-2 and N-2 decreased. The selectivity of O-2/N-2 decreased with increasing operating temperature. The pure gases sorption measurements indicated that the affinity between oxygen and the membranes was appreciable higher than that of nitrogen. According to the X-ray analysis of the complexed membranes, the decreased gas diffusivities were caused by the increase of the packing density. The selectivity of O-2/N-2 was 15 and oxygen permeability for the cobalt complexed membrane with 3 wt % oxygen carrier was 0.33 barrers at 5 degrees C. Furthermore, a dual mode sorption mechanism was utilized to describe the behavior of gas sorption and permeation through the cobalt complexed membrane.