In the title compound, C(15)H(11)ClN(4)OS, the dihedral angle between the nine-membered 5-chloro-indolin-2-one ring system and the benzene ring is 10.00 (6)°. Intra-molecular cyclic N-H⋯O and C-H⋯S hydrogen-bonding inter-actions [graph set S(6)] are present in the N-N-C-N chain between the ring systems. In the crystal, mol-ecules form centrosymmetric cyclic dimers through inter-molecular N-H⋯O hydrogen bonds [graph-set R(2) (2)(8)] and are extended by C-H⋯Cl inter-actions into infinite chains which propagate along [100].