The purpose of this research is to study a new synthesis of LiCrxNi0.5-xMn0.5O2 (x = 0, 0.05 and 0.1) using a co-precipitation method for lithium secondary batteries. Investigations are made of the morphology, cyclic voltammetry and charge-discharge cycling of LiCrxNi0.5-xMn0.5O2/Li cells. The particle size of LiNi0.5Mn0.5O2 has a narrow distribution range from 200 to 300 nm. The peak current of LiCr0.05Ni0.45Mn0.5O2 and LiCr0.1Ni0.4Mn0.5O2 in the 2.7 and 2.9 V regions increases with increasing addition of Cr in LiCrxNi0.5-xMn0.5O2. The discharge capacity of the LiNi0.5Mn0.5O2 electrode is 185 and 150 mAh g(-1) at 1 and 15 cycles, respectively. The fading in capacity of Cr-doped LiNi0.5Mn0.5O2 is less than that of LiNi0.5Mn0.5O2, during cycling. LiCrxNi0.5-xMn0.5O2 cathodes with I M LiPF6 in an ethyl carbonate-dimethyl carbonate (EC-DMC) electrolyte exhibit good cycling performance. (c) 2005 Published by Elsevier B.V.