SnOx thin films were prepared by reactive radio frequency magnetron sputtering with different sputtering powers. X-ray photoelectron spectroscopy suggested that all the films have similar chemical stoichiometry as SnO1.5. X-ray diffraction and transmission electro microscopy results showed that crystal size of the SnOx thin films gradually increases with increase of sputtering power from 50 to 150W. Cyclic voltammetry and galvanostatic charge/discharge cycling measurements indicated that the electrochemical properties of SnOx films strongly rely on their crystal sizes as well as surface morphologies. The SnOx film deposited at sputtering power of 120W exhibits the best electrochemical performances. It could deliver a reversible capacity of 670 mu Ah cm(-2) mu m(-1) at 50 mu A cm(-2) in the voltage range of 0.1-1.2 V up to 50 cycles. (C) 2008 Elsevier Ltd. All rights reserved.