The Li[Li1/5Ni1/10Co1/5Mn1/2]O-2 cathode material was synthesized using a sol-gel method. The Li[Li1/5Ni1/10Co1/5Mn1/2]O-2 was formed with typical hexagonal structure. The discharge capacity of Li[Li1/5Ni1/10Co1/5Mn1/2]O-2 delivered 190 mAh/g at the first cycle. But the discharge capacity gradually increased with cycle number to be 231 mAh/g after 13th cycle and reached 229 mAh/g after 40 cycles with capacity fading ratio of 0.014 %/cycle. The oxidation states of Ni and Co were 21 and 31, respectively, while Mn was in the 4+ oxidation state in the Li[Li1/5Ni1/10Co1/5Mn1/2]O-2. But the oxidation state of Mn was reversibly changed between 4+ and 3+ after the first cycle. (C) 2004 The Electrochemical Society.