Reaction of 4-amino-6-methyl-3-thio-3,4-dihydro-1,2,4-triazin-5(2H)-one (1) with 2-methoxybenzaldehyde, 4-methoxybenzaldehyde, 2-pyridinecarbaldehyde, and 2,4-dichlorobenzaldehyde under classical heating and microwave irradiation in a solventfree system led to the corresponding imines (Schiff bases) 2 -5. All synthesized compounds have been characterized by IR and NMR spectroscopy, mass spectrometry and by X-ray diffraction studies.