The newly developed LiNi0.6Co0.4-xMnxO2 (0.1 < x < 0.3) cathode materials were synthesized by calcining the mixture of NixCoyMn1-x-y(OH)2 and Li2CO3 at 900-940 oC for 15 hr in flowing O2 atmosphere. The NixCoyMn1-x-y(OH)2 precursor was obtained by the chemical co-precipitation method at the pH value controlled by the concentration of NaOH, NH4OH and transition metal sulfate solution. The X-ray diffraction patterns indicated the pure layered hexagonal structure LiNi0.6Co0.4-xMnxO2. The electrochemical behavior of LiNixCoyMn1-x-yO2 powder was examined by using test cells cycled within the voltage range 3-4.3 V at the 0.1C rate for the first cycle and then at the 0.2C rate afterwards. LiNixCoyMn1-x-yO2 cathode materials showed good initial discharge capacity (165-180 mAh/g) and cycling performance. The fading rate was less than 5 % after 20 cycling test. It is demonstrated that LiNixCoyMn1-x-yO2 electrode should exhibit great potential for the future application in lithium-ion battery cathode material.