The two aromatic parts of the title compound, C(16)H(13)ClN(3)O(4), are connected through a conjugated -CH=N-NH-C(O)- fragment, giving an almost planar mol-ecule (r.m.s. deviation 0.08 Å). In the crystal structure, adjacent mol-ecules are linked by N-H⋯O and O-H⋯O hydrogen bonds into a three-dimensional network.