Bis(2-methyl-1H-benzimidazol-3-ium) naphthalene-1,5-disulfonate.

The asymmetric unit of the title compound, 2C(8)H(9)N(2) (+)·C(10)H(6)O(6)S(2) (2-), contains a 2-methyl-benzimidazolium cation and one half of a naphthalene-1,5-disulfonate anion. The formula unit is generated by an inversion center. In the crystal, N-H⋯O hydrogen bonds link the components into chains along [001]. In addition, weak C-H⋯O hydrogen bonds and weak C-H⋯π inter-actions are observed. The methyl H atoms were refined as disordered over two sets of sites with equal occupancy.