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The possibility of using phillipsite- and chabazite-rich tuffs as cation exchangers in the process of barium and cobalt removal from wastewaters is evaluated. Accordingly, fixed beds of phillipsite-rich Neapolitan yellow tuff grains and of chabazite-rich Orvieto-Bagnoregio ignimbrite grains are prepared. After exchanging them in Na(+) form, the relevant breakthrough curves are determined, using 100 mg/l solutions of both cations. Some characteristic dynamic parameters are calculated from these curves, such as length of mass transfer zone, ion exchange capacity in dynamic conditions, dynamic selectivity and efficiency of the process, obtaining information on the conditions under which the process should be carried out. The data collected evidence the good selectivity of both Na-exchanged zeolites for Ba and the poor selectivity for Co, confirming the results of previous tests in equilibrium conditions. The difficulty of eluting barium from the tuff beds during regeneration, suggest a profitable employment of Italian phillipsite- and/or chabazite-rich tuffs in discontinuous processes, especially useful in the treatment of nuclear power plant wastes, in which Ba is removed from the waste through direct addition of powdered zeolite tuff and the resulted sludge is then stabilised-solidified in cement matrices.