A facile synthesis of 1,8-bis-[5,6-diaryl-[1,3,4]-thiadiazino-(3,4-c)-[1,2,4]-triazol-5-yl]-octanes have been carried out by reacting 1,8-bis-(3-mercapto-4-amino-[1,2,4]-triazol-5-yl)-octane with substituted benzoins in presence of potassium hydroxide. The required 1,8-bis-(3-mercapto-4-amino-[1,2,4]-triazol-5-yl)-octane was synthesized by reacting sebacic acid dihydrazide with carbondisulphide and potassium hydroxide followed by the addition of hydrazine hydrate. The parent compound sebacic acid dihydrazide was prepared by refluxing the mixture of sebacic acid and thionyl chloride followed by the addition of hydrazine hydrate. The constitution of synthesized compounds has been delineated on the basis of chemical transformation, elemental analysis, equivalent weight determination and IR, 1H-NMR, mass spectral studies. The title compounds have been screened for their antimicrobial activity against gram-positive as well as gram-negative microorganisms.