4-Cyano-pyridinium hydrogen sulfate.

All non-H atoms of the cation of the title salt, C(6)H(5)N(2) (+)·HSO(4) (-), are essentially coplanar [r.m.s. deviation = 0.005 (1) Å] . In the crystal, N-H⋯O and O-H⋯O hydrogen bonds and weak C-H⋯O and C-H⋯N inter-actions link the mol-ecules into a two-dimensional network parallel to the (001) plane. Weak π-π stacking inter-actions between the pyridine rings of neighbouring mol-ecules further stabilize the structure [centroid-centroid distance = 3.785 (1) Å].