In the title hydrazone derivative, C(15)H(14)N(2)O(5), the benzene rings are twisted by 7.55 (8)° with respect to each other. The azomethine double bond adopts an E conformation. The mol-ecular structure is stabilized by intra-molecular O-H⋯N and N-H⋯O hydrogen bonds, generating S6 ring motifs. In the crystal, mol-ecules are linked into a three-dimensional network by O-H⋯O hydrogen bonds.