The reaction of diethylcarbamic chloride (one mole equivalent), ammonium thiocyanate (two mole equivalents) and thiosemicarbazide (one mole equivalent) in an acetone medium resulted in the formation of the unexpected4,4-dimethyl-2,6-dithioxo-1,3,5-triazinan-1-yl)-3-(diethylaminocarbonyl)- thiourea3in 83% yield. The chemical structure of the title compound was confirmed by IR, NMR and elemental analysis. Further, a suggested mechanism has been proposed to illustrate the route for the formation of the title compound. In addition, theoretical evaluations of the stable geometries of compound3were carried out using semi-empirical molecular quantum calculations with the PM3 method.