2-(2-Hy-droxy-3-meth-oxy-phen-yl)-1H-benzimidazol-3-ium perchlorate.

In the title mol-ecular salt, C(14)H(13)N(2)O(2) (+)·ClO(4) (-), the ring systems in the cation are almost coplanar [dihedral angle = 5.53 (13)°]. Intra-molecular N-H⋯O and O-H⋯O hydrogen bonds generate S(6) and S(5) rings, respectively. In the crystal, the two H atoms involved in the intra-molecular hydrogen bonds also participate in inter-molecular links to acceptor O atoms of the perchlorate anions. A simple inter-molecular N-H⋯O bond also occurs. Together, these form a double-chain structure along [101].