In the title salt, C(6)H(9)N(2) (+)·C(7)H(5)O(3) (-), the carboxyl-ate mean plane of the 4-hydroxy-benzoate anion is twisted by 13.07 (4)° from the attached ring. In the crystal structure, the ions are linked into a two-dimensional network by N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds. Within this network, the N-H⋯O hydrogen bonds generate R(2) (2)(8) ring motifs. In addition, π-π inter-actions involving the pyridinium rings, with a centroid-centroid distance of 3.7599 (4) Å, are observed.
* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.