In the molecule of the title compound, C13H10ClN3OS, the dihedral angles between the plane through the thiourea group and the pyridine and benzene rings are 53.08 (3) and 87.12 (3)°, respectively. The molecules are linked by intermolecular N—H⋯N hydrogen-bonding interactions to form a supramolecular chain structure along the a axis. An intramolecular N—H⋯O hydrogen bond is also present