Benzene-1,3,5-tricarb-oxy-lic acid-5-(pyridin-1-ium-3-yl)-5H-1,2,3,4-tetra-zol-5-ide (1/1).

The asymmetric unit of the title compound, C(6)H(5)N(5)·C(9)H(6)O(6), comprises a full mol-ecule each of neutral trimesic acid (tma) and zwitterionic 5-(pyridin-1-ium-3-yl)-5H-1,2,3,4-tetra-zol-5-ide (ptz). The components are linked into a two-dimensional layer by a combination of O-H⋯O, O-H⋯N, N-H⋯O and N-H⋯N hydrogen bonds parallel to the (10[Formula: see text]) plane. Layers comprising alternating rows of tma and ptz are linked into a three-dimensional network by C-H⋯O and π-π inter-actions between tma and tetra-zolate rings [centroid-centroid distance = 3.763 (2) Å], and between pyridinium and tetra-zolate rings [centroid-centroid distance = 3.745 (2) Å].