A facile synthesis of 4-hydroxy-3-arylthiazolidine-2-thiones through novel domino reactions of aryl isothiocyanates and 1,4-dithiane-2,5-diol under solvent- and catalyst-free microwaveirradiation is reported. This highly atom efficientreaction presumably proceeds via 2-mercaptoacetaldehyde generation/thia-Michael addition/regioselective hemiaminalization domino sequence. This reaction also proceeds