The electrochemical performance of the layered Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O 2 material have been investigated as a promising cathode for a hybrid electric vehicle (HEV) application. A C/Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O 2 cell, cycled between 2.9 and 4.1V at 1.5C rate, does not show any sign of capacity fade up to 100 cycles, whereas at the 5C rate, a loss of only 18% of capacity is observed after 200 cycles. The Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O 2 host cathode converts from the hexagonal to a monoclinic symmetry at a high state of charge. The cell pulse power capability on charge and discharge were found to exceed the requirement for powering a hybrid HEV. The accelerated calendar life tests performed on C/Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O 2 cells charged at 4.1V and stored at 50 o C have shown a limited area specific impedance (ASI) increase unlike C/Li(Ni 0 . 8 Co 0 . 2 )O 2 based-cells. A differential scanning calorimetry (DSC) comparative study clearly showed that the thermal stability of Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O 2 is much better than that of Li(Ni 0 . 8 Co 0 . 2 )O 2 and Li(Ni 0 . 8 Co 0 . 1 5 Al 0 . 0 5 )O 2 cathodes. Also, DSC data of Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O 2 cathode charged at 4.1, 4.3, and 4.6V are presented and their corresponding exothermic heat flow peaks are discussed.