Microwave hydrothermal processing was used to prepare two bismuth oxides, ABi(2)O(6) (A = Mg, Zn) with the unusual oxidation state of Bi5+, which were previously prepared under the limited hydrothermal conditions only. In this work microwave hydrothermal processing for these bismuth oxides was compared with conventional ones. It was found that microwave hydrothermal processing was of greater advantage in kinetics than conventional hydrothermal processing.