4-Cyano-pyridinium dihydrogen phosphate-isonicotinonitrile-phospho-ric acid (1/1/1).

The asymmetric unit of the title compound, C(6)H(5)N(2) (+)·H(2)PO(4) (-)·C(6)H(4)N(2)·H(3)PO(4), contains one 4-cyano-pyridinium cation, one H(2)PO(4) (-) anion, one independent isonicotinonitrile mol-ecule and one independent H(3)PO(4) mol-ecule. The dihedral angle between the mean planes of the separate protonated and unprotonated pyridine rings is 9.93 (8)°. In the crystal, N-H⋯O and O-H⋯N hydrogen bonds and weak C-H⋯O and C-H⋯N inter-molecular inter-actions connect the organic mol-ecules into a two-dimensional network parallel to the ac plane. O-H⋯O hydrogen-bonding inter-actions involving the H(2)PO(4) (-) anions and H(3)PO(4) mol-ecules provide additional support from the inorganic groups Weak π-π stacking inter-actions between the pyridine rings of neighbouring organic mol-ecules [centroid-centroid distances = 3.711 (4) and 3.784 (2) Å] further link the layers into a three-dimensional network.