A K2NiF4-type oxide (Nd0.9La0.1),(Ni0.74Cu0.21Al0.05)O4+delta (NLNCA) has been successfully synthesized by a sol-gel method. The oxygen permeation and stability of the NLNCA membrane under CO2 atmosphere were systematically studied. A steady oxygen permeation flux of 0.39 mL/(min.cm(2)) was obtained through the NLNCA membrane with a membrane thickness of 0.6 mm at 975 degrees C when CO2 was used as the sweep gas. More importantly, the oxygen permeation flux has no significant decrease during 250 h operation, which indicates that the NLNCA membrane is stable under CO2. X-ray diffraction analysis of the spent membrane shows that the membrane retains K2NiF4-type structure and no carbonate was formed even exposed to CO2 after 250 h operation. The results indicate that the NLNCA membrane has a great potential application in supplying oxygen for oxyfuel combustion with CO2 capture. Moreover, the cost of the NLNCA is low, and it is beneficial for industrial application.