Mixtures of 0.1, 0.3. and 0.5 mmol ammonium metatungstate hydrate (AMH), and poly (vinyl alcohol) (PVA) were electrospun by a +20 kV direct voltage to synthesize fibers. Those of 0.5 mmol AMH were further calcined to have PVA removed and crystalline degree improved. At 500 degrees C and 2 h calcination, WO3 nanofibers, including two main stretching modes, 3.24 eV direct energy gap, and 378 nm wavelength violet emission were detected. A possible formation mechanism of WO3 nanofibers was proposed according to the experimental results. (C) 2011 Elsevier B.V. All rights reserved.