The hexagonal MoO3 with high purity was successfully synthesized via a simple solution approach. It was realized by chemical precipitation, hydrothermal treatment and calcination. In the procedure of precipitation, the concentrated HCl played a key role for the formation of the metastable h-MoO3. A variety of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) absorption spectrum and differential thermal analysis (DTA) were used to characterize the product. (c) 2007 Elsevier B.V. All rights reserved.