In the title compound, C(20)H(17)ClN(4)O(2)S, the dihedral angle between the two benzene rings is 65.9 (1)°; the corresponding angle between the 4-chloro-phenyl and thia-diazole rings is 3.4 (8)°. The conformations of the N-H and C=O bonds are anti with respect to each other. The enone groups show a trans configuration. The structure displays intermolecular N-H⋯O, C-H⋯N, C-H⋯S and C-H⋯O hydrogen bonding.