Quinoline derivatives represent one of the most active classes of compounds possesses wide spectrum biodynamic activities and use as potent therapeutic agents. In this research work, a synthesis, characterization and biological evaluation of 6-substituted-2-(substituted-phenyl)-quinoline derivatives bearing 4-amino-1,2,4-triazole-3-thiol ring at C-4 position is described. The synthesis of quinoline derivatives is carried out by the reaction of substituted quinoline-4-carbohydrazides with a mixture of carbon disulphide and potassium hydroxide which further react with hydrazine hydrate to give final compounds. All of these compounds were screened for their in vitro antimicrobial assay against gram (+ve), gram (-ve) bacteria and fungi activity compared with standard drugs viz., Ampicilin, Chloramphenicol, Ciprofloxacin, Norfloxacin, Griseofulvin and Nystatin at different concentrations.