Uptake of iodide radionuclide from model solutions has been tested by means of three various deposit clinoptilolites (of Niný Hrabovec — Slovakia, Mád — Hungary and Wyoming —USA). The samples were chemically modified into more or less Ag-forms and the tests on adsorption were performed using columns packed with grain-sized zeolites. Breakthrough properties of iodide in dependence of competive chloride and phosphate ions were examined, respectively. Mathematical expressions of the adsorption profiles of iodide in Ag-columns as well as some Shilov constants of dynamic experiments were estimated. The highest capacity data to iodide were exhibited by the Ag-modified Slovakian clinoptilolite (102.7 mg/g) and the lowest one by the Hungarian sample (71.6 mg/g).