The optical properties of V(2)O(5)and VO2 films prepared by a radio frequency sputtering were investigated using spectroscopic ellipsometry and measurement of transmittance. It was confirmed that the spectra of the complex refractive index of the V2O5 films are greatly affected by variations in crystalline structure. The spectra of the complex refractive index of the VO2 film showed remarkable change near transition temperature. This result indicates that the metal-insulator transition (MIT) in the VO2 film occurs around 68 degrees C, and the MIT is confirmed by measurement of the transmittance with temperature. (C) 2011 Elsevier B.V. All rights reserved.