The title compound, C(18)H(12)N(2)O, crystallizes in a zwitterionic form. The dihedral angle between the planes of the benzene ring and naphthalene ring system is 13.95 (5)°. An intra-molecular N-H⋯O inter-action results in the formation of a planar six-membered ring, which is oriented at dihedral angles of 13.50 (4) and 4.49 (4)° with respect to the benzene ring and naphthalene ring system, respectively. In the crystal structure, inter-molecular C-H⋯O and C-H⋯N inter-actions link the mol-ecules into a two-dimensional network. π-π contacts between the naphthalene systems [centroid-centroid distance = 3.974 (1) Å] may further stabilize the structure.