Provided herein is a hybrid system for generating oxygen on-board an aircraft for passengers and/or flight crew to breath. The system includes a first chemical oxygen generator component configured to promptly supply oxygen suitable for breathing upon an emergency situation arising and during an initial descent mode. Heat produced from the exothermic decomposition reactions inherent in several types of chemical oxygen generators can be harvested and feed to a second oxygen generator. The second oxygen generator is a solid electrolyte oxygen separation system that catalytically separates oxygen from air inside specialized ceramic materials at high temperatures, about 650° C. to 750° C., using electrical voltage. The ability to feed heat from the first oxygen generator to the second oxygen generator substantially reduces the lag time until the second ceramic oxygen generator is available to take over as the oxygen supply.