1-(4-Chloro­phen­yl)-1H-1,2,4-triazol-5(4H)-one

In the title compound, C₈H₆ClN₃O, the dihedral angle between the 1,2,4-triazole and benzene rings is 4.60 (9)° and an intra­molecular C—H...O inter­action closes an S(6) ring. In the crystal, inversion dimers linked by pairs of N—H...O hydrogen bonds generate R₂²(8) loops and C—H...O inter­actions link the dimers into [100] chains. Weak π–π stacking inter­actions [centroid–centroid distance = 3.644 (1) Å] are also observed.