Abstract: (2-(pyrazin-2-yl)aminmethylenehydrazono)-thiazolidin-4-one, HPzAm4DHotaz, and (2-(pyrazin-2-yl)aminmethylenehydrazono)-3-methylthiazolidin-4-one, PzAm4Motaz have been prepared by the reaction of thiosemicarbazones with chloroacetic acid in presence of triethylamine in toluene using a microwave assisted synthesis and a conventional method, at reflux temperature. While the conventional method carried out other side products as triazoles and thiadiazoles, the cyclization of the thiosemicarbazones using microwave irradiation favours the obtaining of the tiazolidinones as only product and gave better yields, shorter times and any side products were formed