7-(2,2-Dimethylpropanamido)-2-methyl-1,8-naphthyridin-1-ium chloride monohydrate.

The asymmetric unit of the title compound, C(14)H(18)N(3)O(+)·Cl(-)·H(2)O, comprises a substituted amido-naphthyridine cation, a chloride anion and a water mol-ecule of crystallization. Intra-molecular C-H⋯O hydrogen bonds generate six-membered rings, producing an S(6) ring motif. The amido group is twisted from the naphthyridine ring, making a dihedral angle of 17.65 (7)°. The crystal structure is stabilized by inter-molecular N-H⋯O, N-H⋯Cl, O-H⋯Cl (× 2), and C-H⋯O (× 2) hydrogen bonds. These inter-actions linked neighbouring mol-ecules into chains along the a and b axes of the crystal, thus forming mol-ecular sheets parallel to the (001) plane.