In the title compound, C10H7ClN2O2S2, the mean plane of the thioxo-thia-zolidine ring [maximum deviation = 0.032 (2) Å] is inclined to the benzene ring by 12.25 (4)°. There is a strong intra-molecular O-H⋯N hydrogen bond present. In the crystal, mol-ecules are linked via pairs of C-H⋯Cl hydrogen bonds, forming inversion dimers.