A simple, versatile and highly efficient synthesis of 2,4,5-trisubstituted imidazoles by a condensation reaction of benzil or benzoin, aldehydes and ammonium acetate in the presence of urea/hydrogen peroxide (UHP) as a mild and efficient molecular catalyst in refluxing ethanol is described. The present methodology offers several advantages such as green protocol, inexpensive catalyst, high-to-excellent yields, and simple and easy work-up procedure.