The title Schiff base compound, C(18)H(13)NO(2), is a zwitterion, with the naphthol hy-droxy group deprotonated and the imine N atom protonated. It adopts an E configuration about the central C=N double bond. The dihedral angle between the naphthyl ring system and the benzene ring is 1.73 (11)°. An intra-molecular N-H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, adjacent mol-ecules are connected by inter-molecular C-H⋯O hydrogen bonds, forming a supra-molecular ribbon along the b axis.