The title Schiff base compound, C(9)H(11)N(3)O(2)S, was prepared by the reaction of equimolar quanti-ties of 2-hy-droxy-4-meth-oxy-benzaldehyde with thio-semicarbazide in methanol. The mol-ecule adopts a trans configuration with respect to the azo-methine group and an intra-molecular O-H⋯N hydrogen bond generates an S(6) ring. In the crystal structure, mol-ecules are linked through inter-molecu...