Li2MnO3 materials were synthesized at various calcination temperatures by the conventional solid state reaction. The Li2MnO3 powders were characterized by means of XRD, SEM, and TEM analyses. The particle properties of the Li2MnO3 powders, such as their surface morphology and oxygen content, as well as their electrochemical behaviors varied according to the calcinations temperatures. The discharge capacities of the Li/Li2MnO3 cells decreased with increasing calcination temperatures. The resulting Li2MnO3 material was mainly composed of Li2MnO3, sub-LiMnO2, and sub-LiMn2O4 phases. The unexpected reversible discharge capacity of Li/LiNnO(3) cell fabricated in this study originated from the phase transformation between layered LiMnO2 and cubic LiMn2O4 phases in this material. (c) 2006 Elsevier B.V. All rights reserved.