The catalytic effect of trans-3,5-dihydroperoxy-3,5-dimethyl-1,2dioxolane in the presence of HCl has been explored in one-pot condensation reaction of o-phenylenediamines and o-aminobenzenethiol with a variety of aldehydes into their corresponding 2-aryl-1-arylmethylimidazoles and 2arylbenzothiazoles respectively. The reactions were conducted under mild conditions in MeCN at room temperature to afford the products in excellent yields.