On the basis of statistical and dynamical adsorption equilibria the adsorption ability of Ba and Cs by zeolitized tuffs were investigated. Natural tuff of clinoptilolite type originated from the deposit Nizny Hrabovec (East Slovakia) and the tuff of mordenite type originated from the deposit Bartosova Lehotka–Jastraba (Central Slovakia).The determination of Ba- and Cs-concentrations was carried out using Ba (133) and Cs (137) radioindicators. The chosen method allows a very selective and sensitive detection. Some correlations connected with the Theory of Dynamic Adsorption were studied. The kinetics of Cs- and Ba-adsorption on zeolites and the adsorption isotherms were expressed.