Glyoxylic acid (5 tool%) performs as a novel highly water-soluble catalyst for the synthesis of 2-aryl-l-arylmethyl-lH-benzimidazoles from a wide range of substituted o-phenylenediamines and various substituted aldehydes in good to excellent isolated yields (85-95%) using water as solvent at ambient temperature. The remarkable advantages offered by this method are easily and inexpensive available catalyst, simple procedure, mild conditions, much faster (20-40 min) reactions and excellent yields of products.