This work determines the effect of chemical modification on the sorption capacity of natural Turkish zeolite, clinoptilolite, for its potential application as a sorbent. Pore size distribution and surface area are critical for assessing the suitability of the zeolite for sorbent application. Because natural clinoptilolite has small pore sizes and low surface area compared to synthetic zeolites, modification studies have been performed to improve the sorption capacity. The conversion of natural clinoptilolite to the hydrogen form has been carried out by two different ion exchange procedures, namely ammonium exchange followed by calcination and direct treatment with HCl. The natural and modified clinoptilolite samples were characterized by XRD, Al-27 MAS NMR and BET methods.