In this work physical and chemical properties of RNA and its sodium salt (Na-RNA) have been studied at extreme conditions similar to those abundant at the prebiotic stage of chemical evolution. Characterization of dry RNA samples has been performed by thermal analysis (TGA and DTA) and NMR relaxation methods. Aqueous solutions of the above samples have been additionally studied using UV-Vis spectroscopy and dynamic light scattering. It has been shown that the mechanism and rate of thermal destruction, as well as the hydration degree of the samples significantly differ for the two forms of RNA studied. A chemical modification of the solid state RNA samples upon storage includes both oxidation of the nitrogenous bases and hydrolysis of phosphodiester bonds leading to the changes in the absorption spectra and different solubility of the RNA and Na-RNA samples.