A new series of 2-(5-(2-chloroquinolin-3-yl)-3-(aryl)-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)ones 4a-l have been prepared and characterized by IR, NMR and mass spectroscopy. The synthesized compounds have been screened for antimicrobial activity against microbial strains: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogenes, Candida albicans, Aspergillus nig...