In the title compound, C(8)H(8)ClN(3)OS, the whole mol-ecule assumes a planar structure, with an r.m.s. deviation of 0.108 (2) Å, and an intra-molecular O-H⋯N hydrogen bond generates and S(6) and ring motif. In the crystal structure, each of two pairs of inter-molecular N-H⋯S hydrogen bonds connects two mol-ecules, forming inversion dimers with R(2) (2)(8) motifs.