The single-crystal of lithium overstoichiometric Li1 + xCoO2 was synthesized by a flux method using LiCl and Li2O2 flux system. The obtained Li1 + xCoO2 single-crystal is black and has the shape of a plate. Li1 + xCoO2 crystallizes in space group R (3) over barm = 2.8207(2) angstrom and c = 14.0688 (14) angstrom. The structure was determined by a single-crystal X-ray study and refined to the conventional values of R = 1.04% and wR = 1.41% for 44 independent observed reflections. The cobalt state of Li1 + xCoO2 was confirmed by the data of Li-7-MAS-NMR, the magnetic susceptibility measurement and the electrochemical Li insertion/extraction experiments. (C) 2013 Elsevier B.V. All rights reserved.