The mol-ecule of the title compound, C(18)H(13)N(3)O(5), displays an E configuration with respect to the C=N double bond. The dihedral angle between the benzene ring and the naphthyl system is 1.1 (2)°. In the crystal structure, mol-ecules are linked through inter-molecular N-H⋯O and O-H⋯O hydrogen bonds, forming a three-dimensional network.