By using a home-style microwave oven, Al-Al2O3 powder mixture could be heated and Al powder oxidized to convert the Al-Al2O3 powder mixture into an Al2O3 body and, subsequently, this Al2O3 body was sintered. The differences of powder characteristics which resulted from differently processed raw materials affected the oxidation behaviours, and these effects were more serious when a microwave oven was used than when a conventional furnace was used. Heating and oxidation mechanisms are discussed. Also the simultaneous oxidation and sintering of an Al-Al2O3 powder mixture were performed within 1 h by using microwave hybrid heating (MHH), which greatly reduced processing time and energy.