We have synthesized gallium oxide (Ga2O3) nanobelts by heating GaN powders in the conventional furnace. The nanobelts exhibited a unique bicrystalline structure that consisted of two single-crystalline monoclinic Ga2O3 nanobelts, which split along the twin boundary that exists at the centerline. Energy dispersive X-ray spectroscopy and electron energy loss spectroscopy spectra coincidentally indicated the presence of nitrogen in the Ga2O3 nanobelts. Photoluminescence spectra exhibited the visible light emission. We discussed the possible emission mechanisms, including the effect of the nitrogen dopant. (c) 2006 Elsevier B.V. All rights reserved.