Hydrothermal reactions using NaBiO3·nH2O produced a variety of newbismuth oxides that were not prepared by high temperature reaction. Some of them have pentavalent bismuth such as Bi2O4O, LiBiO3, ABi2O6 (A = Mg, Zn) and AgBiO3. When using transition metal or rare-earth metal solutions, new bismuth oxides with trivalent bismuth were obtained. In the case of Cr(NO3)3 solution a chromium bismuth oxyhydroxide, HBi3(CrO4)2O3, was prepared at 180°C, while in A2CrO4 (A = Li, Na, K) solution a new bismuth chromium oxide, Bi8(CrO4)O11, was prepared above 180°C. When A2MoO4 (A = Li, Na, K) solution was used, a new phase appeared above 220°C. By using A2WO4 (A = Li, Na, K) solution β-Bi2O3 and Bi2WO6 were obtained above 220°C.