Vanadium oxide thin films with thickness of about 2000 Å have been prepared by radio frequency sputter deposition using a V 2O5 target in a mixed argon and oxygen atmosphere with different Ar/O 2 ratio ranging from 99/1 to 90/10. X-ray diffraction and X-ray absorption near edge structure spectroscopic studies show that the oxygen content higher than 5% crystallizes a stoichiometric V 2O5 phase, while oxygen deficient phase is formed in the lower oxygen content. The oxygen content in the mixed Ar + O 2 has a significant influence on electrochemical lithium insertion/deinsertion property. The discharge-charge capacity of vanadium oxide film increases with increasing the reactive oxygen content. The V 2O5 film deposited at the Ar/O 2 ratio of 90/10 exhibits high discharge capacity of 100 μAh/cm-μm along with good cycle performance.