Abstract: The partition equilibria of Ce (Ⅳ) between sulphuric acid and N1923 are investigated. The extraction mechanism of Ce (Ⅳ) is clarified viz.: at low aqueous acidity, and at high aqueous acidity,The composition of extractive Ce (Ⅳ) complex is determined by the organic phase saturation with IR and MW.The effects of different solvents and temperatures on the extraction of Ce (Ⅳ) is observed. The concentration equilibrium constant (Kex) and thermodynamical functions (△H.△G and △S) are obtained. The IR study is carried out for trie organic phase.