Ionic diffusion and conductivity in Li2CuO2 and LiCuO2 have been studied by complex impedance measurements. The conductivity of both samples is largely enhanced with increasing temperature and reaches 10(-2)-10(-1) S/m at around 450 K. X-ray diffraction measurements show that a small amount of CuO phase appears with increasing temperature in both samples. High electric conduction would be ascribed to a complicated mechanism containing the ionic and hole conduction. (c) 2006 Elsevier B.V. All rights reserved.