FeOF thin film has been successfully fabricated by reactive pulsed laser deposition for the first time, and its electrochemical behavior was examined as a negative electrode active material in lithium-ion batteries. The electrochemical properties of the as-deposited FeOF thin film during the first charging and discharging have been investigated by the galvanostatic cycling and cyclic voltammetry measurements. By using ex situ X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected-area electron diffraction measurements (SAED), it can be found that FeOF was initially decomposed into Fe-0, LiF, and Fe2O3 after discharging to 1.0 V. The newly formed Fe2O3 is then subsequently reduced into Li2O and Fe-0 after further discharging to 0.01 V. In the subsequent cycle, the reduction peaks at 0.76V and the oxidation-reduction peaks at 1.6 and 1.9 V could be attributed to the reversible decomposition and formation of Li2O with the conversion reaction of Fe2O3 into Fe. (C) 2010 Elsevier Ltd. All rights reserved.