he Cs adsorption capacity of layered sodium silicate ilerite, which has ion exchange ability, was investigated. he amount of Cs ions (Cs+) absorbed from aqueous solution was estimated, and the adsorption/desorption behavior of ilerite was examined by X-ray difraction and thermal analyses and compared with the corresponding properties of clay minerals. Ilerite showed a high adsorption capacity and maintained a high level of adsorption especially in the higher concentration range of Cs+. In ilerite, hydrated Cs+ ions form loosely bonded outer-sphere complexes. In addition, the silicate layer in ilerite creates a rigid channel structure, through which Cs+ ions pass sequentially to penetrate the interlayer deeply; therefore, ilerite is expected to have superior adsorption performance. he adsorbed Cs+ could be detached from ilerite by washing with an aqueous acidic solution, because the surface charges of the silicate layer of ilerite, which contribute to ionic adsorption, are pH-dependent. Ater the desorption of Cs+, the recycled ilerite could again adsorb Cs.