The reaction of 4-(methylsulfonyl)phenylacetohydrazide (3) with carbon disulfide and potassium hydroxide followed by hydrazine hydrate gave 4-amino-5-[4-(methylsulfonyl)benzyl]-4H-[1,2,4]triazole-3-thione (4). The resulting triazole was subjected to cyclocondensation reaction with different phenacyl bromides to afford 6-substituted-3-[4-(methylsulfonyl)benzyl]-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines (5a-i). All structures of the newly synthesized compounds were confirmed by IR, NMR, mass spectral studies and elemental analyses. The newly synthesized compounds were screened for their cytotoxic, antibacterial and antifungal activity. Some of the derivatives have exhibited promising biological activity.