Monoclinic Ga2O3 nanobelts and nanosheets are obtained by a simple chemical route involved with H2O at 950 °C in Ar atmosphere. Electron microscopy observations reveal that the as-synthesized Ga2O3 nanobelts and nanosheets are structurally uniform, single crystalline, and most of them are free of defects and dislocations. The nanobelts are growing along with  facets, and the nanosheets are stacked up by (011) facets. The Raman scattering spectrum of Ga2O3 nanostructures shows a 30 cm-1 redshift at high wave numbers in comparison with that of bulk Ga2O3 powder. The photoluminescence spectrum reveals that there exists a stable blue emission band centered at 460 nm, which is mainly attributed to the oxygen vacancies in the Ga2O3 nanostructures. © 2002 American Institute of Physics.