NH₄⁺ -clinoptilolite samples, dealuminated by means of ammonium hexafluorosilicate were used for morphological and structural investigations. The changes of structure were measured by XRD analysis and surface characteristics measurements. The influence of the dealumination on the morphology was monitored using scanning electron microscopy (SEM). The dissolution-degradation process (amorphous phase formation) was found during dealumination. The products of the isomorphous substitution of the aluminium by silicon exhibit an increase of the specific mesopore surface up to discret Si/Al ratio. The extraframework species are supposed in pore system of dealuminated clinoptilolite.