In the title compound, C(18)H(13)ClN(2)OS, the thia-zolidinone ring is slightly distorted and adopts a envelope conformation. The basal plane is nearly perpendicular to the quinoline ring, forming a dihedral angle of 86.1 (1)°, and makes a dihedral angle of 14.9 (1)° to the benzene ring. The benzene ring is also nearly perpendicular to the quinoline ring, forming a dihedral angle of 89.4 (1)°. In the crystal, non-classical C-H⋯O and C-H⋯N hydrogen bonds link the mol-ecules, forming polymers along b.