Hydrated metal nitrates of Zn, Mn, Ni, Co, Cu, Fe, Cr and Bi, either pure or supported by an acid treated montmorillonite (K10 from Sud-Chemie), were studied using X-Ray diffraction, TG, DTG, DTA, together with MS analysis of gaseous products formed during thermal decomposition. The decomposition products were also analysed by thermoemanation analysis. The metal nitrates were present on the support in the form of crystalline hydrates and not as acetone solvates as supposed earlier. The thermal decomposition of supported metal nitrates started at lower temperatures than those observed for bulk metal nitrates. The supported reagents were tested in different organic oxidation and nitration model reactions. The activities in organic chemical reactions were controlled by the thermal stability of the supported metal nitrates, as expected for reactions involving nitrogen oxides as active intermediates. The suitable reaction conditions were obtained from thermal analysis.