0.5Li(2)MnO(3)-0.5LiMn(0.5)Ni(0.5)O(2) composite cathode material with and without ZnO treatment has been synthesized using carbonate based co-precipitation method for rechargeable lithium ion battery. The X-ray diffraction study confirms that the material has layered LiNi0.5Mn0.5O2 structure along with the formation of the superlattice ordering of Li2MnO3; without any major change in the crystal structure with ZnO treatment. Raman spectroscopy has revealed two different types of ionic arrangements corresponding to space groups of C2/m and R (3) over barm for Li2MnO3 and LiNi0.5Mn0.5O2 respectively. Morphological studies revealed primary particles are of similar to 1 micron size and have sharp, elongated edges. The particles are present as spherical agglomerates (similar to 10 micron). Elemental mapping and X-ray photoelectron spectroscopy confirmed the presence of Zn in the ZnO treated samples. Charge/discharge capacity of the composite cathode materials (with andwithout ZnO coating) increases with number of cycles due to more andmore activation of the Li2MnO3. However, ZnO treated 0.5Li(2)MnO(3)-0.5LiMn(0.5)Ni(0.5)O(2) composite material showed higher charge/discharge capacites attaining saturation in less number of cycles. Lower resistance to charge transfer in the case of ZnO treated sample is responsible for its better performance. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.100204jes] All rights reserved.