Abstract
We reported recently the first polymorph of the title compound [Kuai & Cheng (2011a ▶). Acta Cryst., E67, o2787]. A second polymorph of the title compound, C(15)H(12)N(2)O(2), was unexpectedly obtained by the hydro-thermal reaction of the title compound with manganese chloride in the presence of potassium hydroxide at 413 K. The benzimidazole ring system is almost planar, with a maximum deviation from the mean plane of 0.015 (2) Å. The benzimidazole and benzene rings are inclined at a dihedral angle of 79.00 (1)°. In the crystal, adjacent mol-ecules are connected through O-H⋯N hydrogen bonds into a one-dimensional chain along the [001] direction.