The structural and therapeutic diversity coupled with commercial viability of small heterocyclic molecules has fascinated organic and medicinal chemist. So, a great deal of research was carried out in the field of heterocyclic containing sulphur and nitrogen, because of their immense biological importance. The thiadiazole derivatives posses’ different pharmacological and biological activity. Hence, the search for never effective antimicrobial agents is imperative. It focuses on the problems of cross resistance and better activity against variety of infections. The majority of 1, 3, 4-thiadiazoles are based on the cyclisation of thiaosemicarbazide derivative incorporating this basic structural unit. The structure of new compounds prepared during present investigation has been authentically established by their IR, 1H NMR and Mass spectral studies. The antimicrobial activity of thiadiazole derivatives also reported some of these derivatives exhibit significant and broad spectrum antimicrobial activity. All the synthesized compounds were screened for antibacterial activity against Bacillus subtilis, Bacillus pumilus, E coli and Pseudomonas aureginosa by Disc diffusion method using ciprofloxacin as a standard against Gram positive and Gram negative bacteria. Key Words: Thiadiazole, Thiosemicarbazide, Antimicrobial, Cyclization, Screening