Sodium zeolite X and sodium zeolite A have been exchanged with cesium solutions prepared from three cesium salts (chloride, nitrate, and acetate). Depending on the solution, the cesium cations were found to be located in different sites of the zeolite networks. If cesium acetate solution is used, then cesium reaches sites SII and SIII in the large cavity whereas if nitrate or chloride solutions are put in contact with zeolites, cesium is positioned only in sites SIII. This distribution determines the leaching behavior of the studied zeolites. When the samples were thermally treated to encapsulate partially the cesium cations, it was found that their behavior was different from the one observed in a previous work on cobalt exchanged X and A zeolites