Nitric oxide (NO) is one of the smallest endogenous molecules with particularly interesting aspects roles in biological systems, despite its toxicological potential. Solid carriers have potential biomedical interest in the delivery of exogenous NO for anti-bacterial, anti-thrombic and wound healing applications. In this work, we prepared nanoporous materials from clay based solids, of montmorillonite type, with the main goal of studying its potential in the field of storage and release of nitric oxide for therapeutic applications. Materials were characterized by X-ray diffraction, nitrogen adsorption at −196 °C, TG-DSC and chemical analysis. The kinetic data for the nitric oxide storage and release, in selected materials, was obtained in gas and liquid phases. The released amounts of NO in the liquid phase were within the biological range and, for some materials, a slow release kinetics was obtained with, inclusively, an almost direct relation between the released fraction and time. Toxicological assays with HeLa cells indicated that the materials have low cytotoxicity.