Abstract: The decomposition of LiNiO₂ in the atmosphere was studied by DTA and XRD. The decomposition process was shown as following: LiNiO_2(s) →(650-720℃ )Li₂Ni₈O_10(s)+4Li₂O_(s)+O_2(g) →(850-950℃) Li₂O_(s)+8NiO_(s)+1/2O_2(g) →(1000-1150℃ )NiO_(s)+Li₂O_(g). The activation energies of the above three reaction stages were calculated by Doyle-Ozawa method and Kissinger method as 747.18±1.0 kJ·mol^-1, 932.46±1.0 kJ·mol^-1 and 1126.97±1.0 kJ·mol^-1. The reaction orders and frequency factors can be also determined by Kissinger method. The kinetics equations of each reaction were deduced as ｄα／ｄt＝１．７３６ｘ１０３９ｅ^{－９００００／Ｔ}（１－α）^{１．０５７}； ｄα／ｄｔ＝１８０６×１０^３９ｅ^{－１１１５００／Ｔ}（１－α）^{０．８４４}；ｄα／ｄｔ＝４．２６２×１０４２ｅ^{－１３５０００／Ｔ}（１－α）^{１．２７５.}

Key words: LiNiO₂, decomposition, kinetics, activation energ