Two polymorphs of the title organic salt (a very effective medicinal preparation with the commercial name thiotriazoline), C(4)H(10)NO(+).C(5)H(6)N(3)O(2)S(-), were obtained. The cations and anions are connected by hydrogen bonds and extend into two-dimensional networks. The main packing motifs are an R(4)(4)(12) cluster in the monoclinic form and a chain in the orthorhombic form.