(E)-N'-[(2-Hydroxy-1-naphthyl)methyl-ene]benzohydrazide monohydrate.

In the title compound, C(18)H(14)N(2)O(2)·H(2)O, the dihedral angle between the benzene ring and the naphthalene system is 5.18 (10)°. Intra-molecular N-H⋯O hydrogen bonds influence the molecular conformation. In the crystal, inter-molecular N-H⋯O and O-H⋯O hydrogen bonds are observed as well as π-π inter-actions between the phenyl ring and the substituted ring of the naphthalene [centroid-centroid distance = 3.676 (11) Å].