A series of 2-aryl-4,5-diphenylimidazoles were synthesized by one-step condensation reaction of （aromatic） aldehyde, diphenyl diketone and ammonium acetate（molar ratio 112） in acetic acid under microwave irradiation. Products were characterized by mp, IR, (1H NMR), MS and elemental analysis, and their melting points are identical to those of the known compounds reported in the literature. The reaction time was 411 min and the yield 70%98%. Its a low energy （consumption）, environmentally benign, and easy process.
