In the title compound, C(17)H(15)N(3)O(4), the mol-ecule is in the keto-hydrazone form. Intra-molecular N-H⋯O hydrogen bonds ensure that the mol-ecule is nearly planar (r.m.s. deviation of non-H atoms is 0.098 Å), with the two benzene rings forming a dihedral angle of 10.04 (2)°. In the crystal, inversion dimers are formed via pairs of O-H⋯O hydrogen bonds involving the -CO(2)H groups.