7-Methoxy-2,3-dioxo-1,4-dihydroquinoxalin-6-aminium chloride monohydrate

Single crystals of the title compound, C(9)H(10)N(3)O(3)(+).Cl(-).H(2)O, were obtained by recrystallization from hydrochloric acid. The cations stack along the crystallographic a direction. The 2,3-dioxo-1,4-dihydroquinoxaline group shows a significant deviation from planarity [r.m.s. deviation from the best plane = 0.063 (2) A]. Hydrogen bonding links the cations, chloride anions and water molecules to form an extended three-dimensional architecture.