A series of 3-(4,5-dihydro-5-aryl-li7-pyrazol-3-yl)-4-hydroxyquinolin-2(1H)-ones were synthesized by an efficient microwave assisted synthesis and the product were screened for their antibacterial activity towards Pseudomonas aeruginosa (ATCC-27853), Proteus mirabilis ATCC-19181, Staphylococcus aureus (ATCC-700699), Klebsiella pneumonia (ATCC-10273), Salmonella typhi (ATCC-700931), Entrococci Clinical sample. Compound 3b and 3d found to show good activity against Pseudomonas aeruginosa, Salmonella typhi and Klebsiella pneumonia. © 2015, Sphinx Knowledge House. All rights reserved.