In this study, a new metastable phase of crystallized MoO3 center dot 0.3H(2)O nanobelts was successfully synthesized using a simple synthetic route. The synthesized nanobelts are highly crystalline and have lengths up to several tens of micrometers. Based on the experimental observations, a possible reaction model, solid-solution-solid, was proposed for the formation of the nanobelt structures. (C) 2008 Elsevier B.V. All rights reserved.