Silicon oxide powders with different oxygen contents and particle sizes have been examined as anode materials for lithium ion batteries. SiO0.8 electrode can provide a reversible capacity of ca. 1600 mA h/g over a voltage range from 0.02 to 1.4 V vs. Li. The capacity drops with the increase in the oxygen content. Limited lithium insertion, however, alleviates the host volume expansion and thereby significantly improves the cyclability. In addition, the cycle performance is also dependent on the electrode fabrication method. By powder mixing and pressing, the electrode shows a larger insertion capacity, but the use of N-methyl-pyrrolidone (NMP) solvent for dispersing PVdF binder suppresses the capacity fade on cycling,