Abstract—New 4,4'-(4,6-dimethoxy-1,3-phenylene)bis{2-[2-(substituted benzylidene)hydrazinyl]thiazole} derivatives (5a–5j) have been synthesized from the corresponding 1,1'-(4,6-dimethoxy-1,3-phenylene)bis(2,2- dibromoethanone) and substituted thiosemicarbazones by the conventional method and under microwave irradiation. Structures of the synthesized compounds were characterized by FT-IR, 1H, and 13C NMR and Mass spectra. The products were evaluated for their in vitro antibacterial activity against Gram-positive and Gramnegative stains. Some of the compounds 5b, 5f, 5h demonstrated high activity against B. subtilis (+ve), compound 5c exhibited high activity against E. coli (–ve) and P. aeruginosa (–ve) stains. Among the titled compounds also evaluated for their in vitro antimycobacterial activity, the product 5b demonstrated pronounced antimycobacterial activity against M. bovis stain.