LixMnO2 (x=0.302) was synthesized by chemical lithiation, using a formaldehyde reducing agent and a LiOH lithium source in an aqueous media. The electrochemical properties and structural stability of the product were characterized by X-ray diffraction and charge-discharge measurements. The chemically lithiated LixMnO2 had a first charge and discharge capacity of 86.2 and 265 mAh/g, respectively, with good cycling behavior. Based on the electrochemical results of the first charge, a two-step mechanism of LixMnO2 lithiation is proposed. gamma-MnO2 is first oxidized by formaldehyde, and then Li diffuses into the gamma-MnO2 lattice. (C) 2009 Elsevier B.V. All rights reserved.