The title compound, C(12)H(10)N(2)O(2)·H(2)O, crystallizes as a zwitterion in which the pyridine N atom is protonated and the carboxyl OH group is deprotonated. The benzene and pyridinium rings are inclined at a dihedral angle of 54.93 (1)°. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional supra-molecular network.