The phenomenon of metal-insulator transition (MIT) in polycrystalline VOx thin films and their preparations have been studied. The films were prepared by sputtering of vanadium thin films succeeded by Rapid Thermal Annealing (RTA) in oxygen ambient at 500 degrees C. Crystalline, compositional, and morphological characterizations reveal a continuous change of phase from vanadium metal to the highest oxide phase, V2O5, with the time of annealing. Electrical MIT switching has been observed in these films. Sweeping mode, electrode area, and temperature dependent MIT has been studied in Pt/VOx/Pt vertical structure. The important parameters for MIT in VOx have been found to be the current density and the electric field, which depend on carrier density in the films. (c) 2005 Published by Elsevier B.V.