The layered LiNi0.5Mn0.5O2 used as a cathode material for lithium-ion batteries was synthesized from precursor Ni0.5Mn0.5CO3 prepared via a carbonate co-precipitation method. The precursor Ni0.5Mn0.5CO3 was synthesized by the addition of KHCO3 to an aqueous solution of Ni, Mn sulphates. The powder LiNi0.5Mn0.5O2 was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Spherical LiNi0.5Mn0.5O2 with well development layered structure was obtained by the carbonate co-precipitation method. The LiNi0.5Mn0.5O2 samples adopted the α-NaFeO2 structure with a space group R-3m. Galvanostatic charge-discharge behavior of the LiNi0.5Mn0.5O2 cathodes delivered a initial charge and discharge capacity of 144.4 mAh/g and 140.2 mAh/g, respectively in the voltage range 2.5-4.5V at a discharge rate of 0.02A/g. The capacity showed no dramatic capacity fading during 50 cycles.