Considering the biological properties reported for the purified natural clinoptilolite, NZ, we prepared and Li-enriched forms aimed at release matrices for biomedical applications. The raw material and obtained solid samples were characterized by means of atomic absorption spectroscopy, X-ray diffraction, 27 Al and 19Si MAS nuclear magnetic resonance, and nitrogen adsorption. The results demonstrate the structural stability ofthe materials after the different transformations applied. The chemical behavior of the samples in bi-distilled water and hydrochloric acid was studied by pH and conductivity measurements. A preliminary study related with the liberation ofK and Li in aqueous medium was carried out atomic absorption spectroscopy. The studies showed that the release of both ions from the solid sample and that lithium is released faster than potassium in both dissolution me is favored in HCl solutions. (C) 2009 Elsevier B.V. All rights reserved.