ABSTRACT: In the cation of the title compound, C(6)H(6)N(5) (+)·HSO(4) (-), the pyridine and tetra-zole rings are close to being co-planar [dihedral angle = 3.98 (7)°]. In the crystal, the ions are linked by O-H⋯O, N-H⋯O and N-H⋯(O,O) hydrogen bonds, resulting in chains.