(E)-4-{2-[(2-Hy-droxy-naphthalen-1-yl)methyl-idene]hydrazinecarbon-yl}pyridinium nitrate.

The title compound, C(17)H(14)N(3)O(2) (+)·NO(3) (-), is an aroylhydrazone-based material consisting of a 4-(hydrazinecarbon-yl)pyridinium cation and a nitrate anion. In the cation, the dihedral angle between the benzene ring and the naphthalene ring system is 2.20†(7)°. In the cation, the configuration about the C=N bond is E. There is an intra-molecular O-H⋯N hydrogen bond in the cation, and the supra-molecular structure is stabilized by inter-molecular N-H⋯O hydrogen bonds and weak C-H⋯O contacts between the cation and the nitrate anion.