10.22376/ijpbs.2019.10.1.p1-12 Volume 3 Issue 3 2012 (July - September) Several thiazoles and pyrazolone carrying heterocyclic nucleus were synthesized and tested as antimicrobial agents. All compounds and some of the nitro substituted derivatives have effective antibacterial properties against Gram positive bacteria ( lessThan i greaterThan Staphylococcus aureus lessThan /i greaterThan NCCS 2079 and lessThan i greaterThan Bacillus cereus lessThan /i greaterThan NCCS 2106), Gram negative bacteria ( lessThan i greaterThan Escherichia coli lessThan /i greaterThan NCCS 265 and lessThan i greaterThan Pseudomonas aeruginosa lessThan /i greaterThan NCCS2200). The antifungal activity of synthesized compounds were studied by disc diffusion method against the organisms of lessThan i greaterThan Aspergillus niger lessThan /i greaterThan NCCS 1196 and lessThan i greaterThan Candida albicans lessThan /i greaterThan NCCS 3471. The chemical structures of these newly synthesized compounds were characterized by lessThan sup greaterThan 1 lessThan /sup greaterThan H-NMR, Mass, and IR spectral data. L.K.Ravindranath, E.V.Suresh Kumar, K.Srikanth Y.N.Spoorthi And P.Phebe Thiazole derivatives, Pyrazolones derivatives, microwave irradiation, antimicrobial activity 52-59