N-(2-Chloro-4-nitro-phen-yl)maleamic acid monohydrate.

The title compound, C(10)H(7)ClN(2)O(5)·H(2)O, crystallizes with a half-mol-ecule each of N-(2-chloro-4-nitro-phen-yl)maleamic acid (located on a mirror plane) and water (located on a twofold rotation axis) in the asymmetric unit. The main mol-ecule is planar by symmetry and its conformation is stabilized by an intra-molecular O-H⋯O hydrogen bond. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.