The hybrid pulse power characteristics (HPPC) of Li(Ni0.8Co0.15Al0.05)O-2 and Li-1.1(Ni1/3Co1/3Mn1/3)(0.9)O(2)electrode materials have been evaluated according to the FreedomCAR test manual and found to meet the power requirements for HEV applications. In addition to its excellent power capability, Li-1.1(Ni1/3Co1/3Mn1/3)(0.9)O-2 electrode material has shown much better safety characteristics than the Li(Ni0.8Co0.15Al0.05)O-2 electrode material. To investigate the reason for this finding, Li(Ni0.8Co0.15Al0.05O2 and Li-1.1(Ni1/3Co1/3Mn1/3)(0.9)O-2 powders were chemically delithiated using NO2BF4 oxidizer in an acetonitrile medium. The thermal gravimetric results show that both Li-0.45(Ni0.8Co0.15Al0.05)O-2 and Li-0.55(Ni1/3Co1/3Mn1/3)O-2 obtained powders release oxygen starting from 190 and 250 degrees C with an overall oxygen loss of 11 and 6 wt% at 600 degrees C, respectively. The reactivity of the delithiated powders with several electrolytes was studied by differential scanning calorimetry (DSC) and accelerated rate calorimetry (ARC) techniques. The relationship between the safety characteristics of Li-0.45(Ni0.8Co0.15Al0.05)O-2 and Li-0.55(Ni1/3Co1/3Mn1/3)O-2 powders and their thermal stability was discussed in light of their structural rearrangement during thermal heating. Published by Elsevier B.V.