In the title mol-ecular salt, C(16)H(13)N(2)OS(+)·HSO(4) (-), the thia-zolo[3,2-a]benzimidazolium ring system is roughly planar [maximum deviation = 0.046 (3) Å] and makes a dihedral angle of 58.22 (11)° with the benzene ring. The meth-oxy group is almost coplanar with its attached benzene ring [C(meth-yl)-O-C-C = -1.6 (5)°]. In the crystal, the cation is linked to the anion by a bifurcated N-H⋯(O,O) hydrogen bond, generating an R(1) (2)(4) ring motif. The ion pairs are then connected by a C-H⋯O hydrogen bond into inversion dimers and these dimers are further linked by O-H⋯O hydrogen bonds into an infinite tape along [100]. A π-π stacking inter-action [centroid-to-centroid distance = 3.5738 (18) Å] and a short inter-molecular contact [S⋯O = 2.830 (3) Å] are also observed.