The possible application of natural zeolite clinoptilolite as filler in permeable reactive barriers (PRBs) for protection of groundwater from contamination by heavy metals were investigated. For simulation of underground dynamic conditions for the column experiments on the fixed natural zeolite layer were performed by passing the binary aqueous solution of cadmium and zinc through the column by down-flow mode at flow rates of 1, 2, 3 and 4 mL/min. From the obtained column results the distribution coefficient (K d ) and retardation coefficients (R d ) were calculated in order to estimate the zeolite potential in sorption and retardation of cadmium and zinc in the barrier. The hydrodynamic dispersion coefficient (D L ) and hydrodynamic dispersion retardation coefficient (D LR ) were calculated as well in order to estimate the impact of the hydrodynamic dispersion on the contaminant plume and possible bypassing of the barrier. For all flow rates tested, the highest values of K d and R d were obtained for cadmium compared to zinc, pointing on better distribution and retardation od cadmium in zeolite layer. The reason for that is smaller hydrated ionic radius of cadmium than zinc, making it more mobile, and thus easier to bind on free active zeolite sites. With increasing in flow rate the difference between the K d and R d of cadmium and zinc is lower due to the shorter contact time at which to competition effect is less pronounced. The D L and D LR values for both ions increase with increasing in flow rate, thus increasing their spreading in the porous media caused by hydrodynamic dispersion, which at the end leads to bypassing of the barrier. The best distribution and immobilization of the ions inside the zeolite barrier, alongside their minimum spreading is achieved for the lowest flow rate of 1 mL/min (0.01277 m/min) which, among all tested flow rates, is the closest to the average flow of the groundwater (≈ 0.000003 m/min). The obtained results pointing on possible application of the natural zeolite clinoptilolite as filler in permeable reactive barriers for protection of groundwater from heavy metals pollution.