3-Ethyl-1H-1,2,4-triazole-5(4H)-thione.

The mol-ecule of the title compound, C(4)H(7)N(3)S, exists as the thione tautomer in the solid state. The asymmetric unit consits of one mol-ecule in which all atoms are located on a crystallographic mirror plane. In the crystal, adjacent mol-ecules are linked by N-H⋯N and N-H⋯S hydrogen bonds into chains running along the a axis. π-π stacking inter-actions between the triazole rings [centroid-centroid distance = 3.740 (1) Šand inter-planar distance = 3.376 Å] may further stabilize the structure.