A kinetic study of the dehydration and decomposition of tetrahydrated CoII methane-sulphonate has been carried out in an argon flow by TG at constant temperature as well as with a linearly rising temperature. The thermal dehydration occurs in two steps regulated by random nucleation, A2 and A3, while the decomposition of the anhydrous salt follows first-order kinetics, F1, where the rate-controlling step is a nucleation process in which there is equal probability of nucleation at each active site. The kinetic parameters obtained at three heating rates are in good agreement; however, the values of kinetic parameters estimated isothermally are smaller than those estimated dynamically.