In the title compound, C(9)H(9)N(3), the 12 non-H atoms are essentially planar (r.m.s. deviation = 0.068 Å). The maximum deviation from planarity is reflected in the torsion angle between the β-N atom of the hydrazinyl residue and the quinolinyl N atom [N-N-C-N = -12.7 (3)°]; these atoms are syn. In the crystal, supra-molecular layers in the bc plane are formed via N-H⋯N hydrogen bonds.