(1− x)Li[Ni0.20Li0.20Mn0.60]O2–xLi[Co0.50Li0.167Mn0.333]O2 solid solutions (x =0, 0.2, 0.4, 0.6, 0.8, and 1.0) have been prepared by a simple combustion method and investigated using X-ray diffraction (XRD), galvanostatic charge/discharge cycling, and cyclic voltammetry. The XRD analysis showed that single-phase compounds were obtained for all the compositions. Under the cycling condition of voltage range of 4.8–2.0V and a specific current of 100mAg−1 at 30°C, the first discharge capacity was found to exhibit the maximum value of 265mAhg−1 for Li[Ni0.16Co0.10Li0.193Mn0.547]O2 (x =0.2). Together with its excellent cycling property due to the structural stability, the observed capacity has potential for high capacity applications. It was also observed that the discharge capacity rapidly decreased during the cycling, when x is larger than 0.20. This implies that the charge/discharge mechanism of Ni-rich compounds is clearly different from that of Co-rich compounds, as being reflected in the evolution of cyclic voltammetry results.