A simple, efficient and eco-friendly one pot synthesis method has been developed for ultrasound induced synthesis of biologically significant 2-aryl-1-arylmethyl-1H-benzimidazoles in EtOH/H2O solvent mixture using Amberlite IR-120. The catalyst is recyclable without loss of activity. The method provides several advantages such as green solvent, simple work-up procedure, shorter reaction time and higher yield.