A novel lithium insertion material of LiCo1/3Ni1/3Mn1/3O2 was reported for advanced lithium-ion batteries. LiCo1/3Ni1/3Mn1/3O2 (R 3 m; a=2.862(2)Å and c=14.227(8)Å in hexagonal setting) shows about 200mAhg−1 of rechargeable capacity with rate capability as high as 1.6Ag−1 between voltages of 2.5 and 4.6V. Preliminary cycle tests of a Li/LiCo1/3Ni1/3Mn1/3O2 cell were also carried out for 30 cycles and shows that loss of rechargeable capacity was negligible. Thermal behavior of fully charged LiCo1/3Ni1/3Mn1/3O2 was examined by differential scanning calorimetry and shown that the exothermic reaction of □0.88Li0.12Co1/3Ni1/3Mn1/3O2 with electrolyte is much milder than that of □NiO2 or □CoO2. From these results we have discussed whether or not this material can be used for advanced lithium-ion batteries.