The lithium electrochemistry of SiO2 thin film prepared by reactive radio frequency sputtering has been investigated for the first time. The reversible discharge capacities of SiO2/Li cells cycled between 0.01 and 3.0 V are found in the range from 416 to 510 mAh/g during the first 100 cycles. By using ex situ transmission electron microscopy, selected-area electron diffraction and X-ray photo-electron spectroscopy measurements, both Li-Si alloying process and the reversible conversion reaction of SiO2 into Li2Si2O5 are proposed in the lithium electrochemical reaction of SiO2. SiO2 film electrode with high-reversible capacity and good cycle performance exhibits it potential anode material for future lithium-ion batteries. (C) 2007 Elsevier B.V. All rights reserved.