Solid solution materials of Li2CUO2 and Li2NiO2 were studied with respect to their electrochemical performance and crystal structure. The Li2CuO2-Li2NiO2 system shows a solid solution over the whole composition range with the orthothombic structure. Pure Li2CuO2 has a reversible capacity of only 100mA h/g, and the capacity of Li2Cu1-xNixO2 increased with increasing the content of Ni. The maximum capacity of 250mA h/g is obtained for Li2Cu0.5NiO2, and it exhibits a good reversibility for charge and discharge cycles. The orthorhombic Li2CuO2 undergoes a phase change to the monoclinic LiCuO2 during lithium deintercalation, while nickel-rich compositions show a new phase that is different from either the original orthorhombic or monoclinic structure. (c) 2006 Elsevier B.V All rights reserved.