The asymmetric unit of the title compound, C(15)H(13)N(3)O(5), contains two independent mol-ecules. Each mol-ecule displays an E configuration with respect to its C=N double bond. The dihedral angles between the two benzene rings are 11.1 (2) and 10.9 (2)° in the two mol-ecules. In the crystal structure, mol-ecules are linked through inter-molecular O-H⋯O hydrogen bonds, forming chains running along the a axis.