A single phase of Li2CuO2 was successfully prepared by solid state reaction. The crystal structure was refined by Rietveld method using a synchrotron radiation source. Electronic structures of x = 0 and 1 in Li2-xCuO2 were determined using the first principle calculation. We will discuss electrochemical properties of Li2CuO2 and changes in electronic structure of Li2-xCuO2, using both the information obtained from the calculation and that obtained experimentally. These results confirmed that Li-extraction of Li2CuO2 resulted in the oxidation of Cu2+ or O2-. The cuprate-based cathode materials have the potential showing high energy density. The calculation of electronic state will play a major role in designing the materials for Li-batteries. (C) 2010 Elsevier B.V. All rights reserved.