1H-Benzimidazol-3-ium-2-carboxylate dihydrate

The title compound, C(8)H(6)N(2)O(2)center dot 2H(2)O, crystallized as a zwitterion with the carboxyl group deprotonated and the imidazole group protonated. The dihedral angle between the benzimidazole ring and the pendant -CO(2) group is 0.62 (2)degrees. In the crystal, molecules are linked into a three-dimensional network by N-H...O and O-H...O hydrogen bonds.