Potassium nickel hexacyanoferrate(II))s (KNiFC) were incorporated in the porous matrix of chabazite by successive impregnation with Ni(NO3)(2) and K4Fe(CN)(6). The loading percentage of KNiFC crystals on chabazite increased with repeated times of impregnation. The ion-exchange equilibrium of Cs+ in KNiFC-loaded chabazite (CFC) was attained within 2 days. Relatively large distribution coefficients of Cs+, K-d,K-Cs, above 10(4) cm(3)/g were obtained, irrespective of coexisting NaNO3 concentration. There is a large difference between the K-d value of Cs-137 and those of other nuclides; the separation factor of Cs/Sr (alpha(Cs/Sr) = K-d,K-Cs/K-d,K-Sr) was estimated to be above 10(4). The breakthrough curve for Cs+ through the column packed with CFC exhibited a symmetrical S-shaped profile, and this exchanger proved to be effective for the selective removal of radiacesium from waste solutions containing highly concentrated NaNO3.