A series of mono and bis-1,2,3-selenadiazole derivatives have been synthesized by the oxidative cyclization of mono and bis semicarbazones of 2-(3-oxo-1,3-diarylpropyl)-1-cyclohexanones using selenium(IV) oxide. The newly synthesized compounds were evaluated for their in vitro antimicrobial activity against Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 11632) and Candida albicans (ATCC 90028) and in vitro antituberculosis activity against Mycobacterium tuberculosis H37Rv (MTB). Among these compounds, 1,3-di(4-chlorophenyl)-3-(4,5,6,7-tetrahydro-1,2,3-benzoselenadiazol-4-yl)-1-propanone (2h) and 3-(4-chlorophenyl)-1-(4-methylphenyl)-3-(4,5,6,7-tetrahydro-1,2,3-benzoselenadiazol-4-yl)-1-propanone (2g) were found to be the most active compounds with MIC of 3.3 and 3.5 μM respectively against MTB.