2-Amino-3-carb-oxy-pyridinium chloride hemihydrate.

The asymmetric unit of the title compound, C(6)H(7)N(2)O(2) (+)·Cl(-)·0.5H(2)O, consists of two protonated 2-amino-3-carb-oxy-pyridine cations, two chloride anions and one mol-ecule of water. The crystal packing can be described as alternating layers of cations and anions parallel to (110), which are linked together by O(w)-H⋯Cl inter-actions. In the crystal, four types of classical hydrogen bonds are observed, viz. cation-anion (O-H⋯Cl and N-H⋯Cl), cation-cation (N-H⋯O), cation-water (N-H⋯O(w)) and water-anion (O(w)-H⋯Cl), resulting in the formation of an infinite three-dimensional network.