Abstract: The adsorption of Np(Ⅴ) on Zhangzhou illite was studied as a function of solid-to-liquid ratio, pH, ionic strength and Np(Ⅴ) concentration, by using a batch experimental method. Np(Ⅴ) adsorption on Zhangzhou illite is shown to be sensitive to pH, whereas it is insensitive to ionic strength. 2SPNE SC/CE model, developed from Puy-en-Velay illite (France), cannot interpret both titration and adsorption data of Zhangzhou illite. A new adsorption model was constructed with the framework of 2SPNE SC/CE model to interpret the data. Comparing with 2SPNE SC/CE model, the site capacity of the new model is much lower, and corresponding constants of protolysis and complexation reactions are quite different as well. The reason for these differences may be due to the fact that the specific surface area of Zhangzhou illite is lower, and the ratio of isomorphous substitution (i.e. content of Fe₂O₃ and MgO) in Puy-en-Velay illite is higher than the one of Zhangzhou illite. The results are useful for predicting more accurately the Np(Ⅴ) adsorption on illite originated from different regions, and provide references for the siting of high-level radioactive waste repository in China.