In the title compound, C9H9N3OS, the plane of the benzene ring forms a dihedral angle of 33.40 (5)° with that of the triazole group. In the crystal, mol-ecules are linked by O-H⋯N hydrogen bonds involving the phenol -OH group and one of the unsubstituted N atoms of the triazole ring, resulting in chains along [010]. These chains are further extended into a layer parallel to (001) by weak C-H⋯N hydrogen-bond inter-actions. Aromatic π-π stacking [centroid-centroid separation = 3.556 (1) Å] between the triazole rings links the layers into a three-dimensional network.