2,3-Diamino-pyridinium 4-hydroxy-benzoate.

In the title compound, C(5)H(8)N(3) (+)·C(7)H(5)O(3) (-), the pyridine N atom is protonated. In the 4-hydroxy-benzoate anion, the carboxyl-ate group is twisted slightly out of the benzene ring plane by an angle of 3.77 (5)°. The protonated N atom and one of the two amino groups are hydrogen-bonded to the 4-hydroxy-benzoate anion through a pair of N-H⋯O hydrogen bonds, forming an R(2) (2)(8) ring motif. The crystal structure is further stabilized by O-H⋯O and C-H⋯O hydrogen bonds and π-π inter-actions involving the pyridinium rings [centroid-centroid distance of 3.6277 (5) Å], leading to the formation of a three-dimensional network.