In this paper, a description of a process for synthesizing MoO3 nanoslabs without using any catalyst is given. The size of the MoO3 nanostructures varying with time are clearly resolved. Time-dependent relationships vs the thickness and width of the as-grown MoO3 nanoslabs are demonstrated. Both X-ray diffraction pattern and transmission electron microscopy images indicated that MoO3 nanoslabs belong to the orthorhombic structure. Three different molybdenum-oxide bondings are differentiated by the Raman spectroscopy. Cathodoluminescene showed a significant red-orange peak based on the band structure of the MoO3. (c) 2007 The Electrochemical Society.