Novel hybrid derivative of quinoline-2-one substituted thiadiazole derivatives tested as antimicrobial activity on Escherichia coli, Pseudomonas aeruginosa and gram-positive bacteria Staphylococcus aureus, Bacillus substilis at 100 µg/ml concentration using cup-plate agar diffusion method. All derivatives of quinoline-2-one substituted thiadiazole were synthesized, purified and characterized using various physiochemical and spectral analysis. Among the all synthesized novel hybrid derivatives, three compounds 4b, 4c and 4f shows promising antibacterial activity as compared to standard drug Ciprofloxacin. The synthesis of new agents, active against resistant organism is of critical importance despite continued efforts to discover improved antimicrobial agents, there has been little success towards discover of antimicrobial agents. The compounds having fluoro substitution at 4th & 2,4-dichloro positions showed satisfactory antibacterial activity.