In the title compound, C(17)H(18)N(2)O(6), the mol-ecule is slightly twisted, with a dihedral angle of 18.1 (2)° between the two benzene rings. In the crystal structure, mol-ecules are linked into a network by inter-molecular N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds. An intra-molecular O-H⋯O hydrogen bond is also present.