The title compound, C14H13ClN2O2S, crystallized in the enantiomorphic defining hexagonal space group P61 [Flack parameter = −0.02 (7)]. The partially hydrated form of the same compound, crystallizing in the triclinic space group P-1, has been reported previously [Kia et al. (2009b). Acta Cryst. E65, o1119], as has the crystal structure of the bromo derivative, also crystallizing in the space group P-1 [Kia et al. (2009a). Acta Cryst. E65, o821]. The title molecule is non-planar with the planes of the benzene rings being inclined to one another by 76.62 (13)°, and has an E conformation about the C=N bond. In the crystal, molecules are linked via N—H⋯O hydrogen bonds forming 61 helical chains running along [001]. The chains are linked via C—H⋯O hydrogen bonds, C—H⋯π interactions and short Cl⋯O [3.015 (3) Å] interactions, forming a three-dimensional structure.