All non-H atoms of the title compound, C(6)H(7)N(3)OS, which exists in the thione form, lie in a common plane (r.m.s. of non-H atoms = 0.08 Å). The amino group of the -NH-NH(2) substituent forms an intra-molecular hydrogen bond to the S atom. The terminal -NH(2) group is pyramidally coordinated; it forms a weak N-H⋯O and a weak N-H⋯S hydrogen bond. Furthermore, the N atom is an acceptor for a C-H⋯N contact. The amino group of the ring is a hydrogen-bond donor to the carbonyl O atom of an adjacent mol-ecule, this inter-action giving rise to a linear chain motif running along the b axis.