LiNi1/3Co1/3Mn1/3O2 has been prepared by solid-state reaction as a novel positive electrode material for lithium-ion batteries. The structural evolution of the material with charge potential is studied using X-ray diffraction. The electrochemical performance of this material is investigated using cyclic voltammetry and galvanostatic cycling. The formation and composition of the solid electrolyte interphase layer on the material are studied by Fourier transform infrared spectroscopy at various potentials and compared with those formed under other conditions. These studies lead to questions of compatibility between the electrode and the electrolyte components and the necessity of surface modification to the electrode material. (C) 2004 The Electrochemical Society.