Abstract: MoO3 nanobelts were synthesized at different temperatures for different reaction times, using Mo powers and H2O2 as raw materials in the absence of any surfactants and templates. The products were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that the prepared products were composed of MoO3 nanobelts with uniform sizes. The nanobelts were 80-100 nm in width, 20 nm in thickness and several tens of micrometres in length. It was found that the morphology of MoO3 nanobelts could be influenced by adjusting the technology parameters, such as reaction temperature and medium.