The facile synthesis of 3-methyl-(III), 3,7-dimethy -6'(7'H)-oxo spiro[cyclohexane-1,3'(4'H)-[2H] thiazolo[3,2-b]-s-tetrazines](IV) and 3-methyl-6,7' -dihydro spiro[cyclohexan-1,3'(4'H)- [2H]thiazolo [3,2-b]-s-tetrazine](V)have been accom plished by reaction of 3-methyl-7,8,10,11- tetaaza spiro[5,5]undecane-9-thione (II) with chlor oacetic acid, α -bromopropionic acid, 1,2- dibromoethane respectively. A reaction of II, obtai ned by reaction of 3-methylcyclohexanone (I) and thiocarbo hydrazide, with phenacyl bromide has been studied in varying conditions leading to the formation of 6'-aryl-3-methylspiro[cyclohexa ne-1,3'(4'H)-[2H]thiazolo[3,2-b]-s-tetrazine] (VII). The structures II-VII have been established by elemental analysis, IR, 1 H NMR and mass spectral data. The sulphur containing compounds III -VII were screened for their antimicrobial activity.