The disclosure provides for oxygen separation from air by utilizing an initial oxygen carrier which undergoes an endothermic reduction reaction to produce a carrier product and gaseous oxygen. The gaseous oxygen is withdrawn, and the carrier product is subsequently further reduced with a fuel in a combustion process, releasing heat and generating a oxygen acceptor. The oxygen acceptor is oxidized in an exothermic reaction. The method thus couples the exothermic oxidation reaction, the endothermic reduction reaction, and the chemical energy supplied by the fuel for a net heat release. In an embodiment, the initial oxygen carrier is CuO, the carrier product is Cu.sub.2O, and the oxygen acceptor is Cu.
 The United States Government has rights in this invention pursuant to the employer-employee relationship of the Government to the inventors as U.S. Department of Energy employees and site-support contractors at the National Energy Technology Laboratory.