Well-defined mondispersed iron oxide particles can be synthesized in conventional hydrolysis approaches, but the synthesis generally takes two to seven days. Microwave hydrothermal approaches offer the possibility of significantly reducing synthesis time. This work demonstrates the feasibility of microwave synthesis in large scale. The batch size was 5 L, and the holding time was two hours. The crystallinity of the powders and the morphology and the monodispersity of the synthesized particles were comparable to those produced from conventional approaches. The particle size was in the nanosize range. The results indicated that for synthesis of monodispersed Fe2O3 nanopowders, it is possible to achieve the production rate of a 2.1 m(3) conventional reactor with a 5 L microwave accelerated reactor.