The thermal decomposition of molten CsSO3NH2, NH4SO3NH2, RbSO3NH2, TISO3NH2, NaSO3NH2 and KSO3NH2 was studied by means of thermogravimetry. A different behaviour of decomposition of the K and Na salts on the one hand, and the other salts on the other, was found. While the decomposition of CsSO3NH2, NH4SO3NH2, RbSO3NH2 and TISO3NH2 starts immediately on reaching the experimental temperature, the decomposition of the Na and K amidosulfonates starts after an incubation time. The activation energies of thermal decomposition of the salts studied were determined.