Abstract: A series of 3-[(3-phenyl-5-thioxo-1,5-dihydro-4H-1,2,4-triazol-4-yl)imino]-1,3-dihydro-2H-indole-2-one derivatives were synthesised through the nucleophilic substitution at carbonyl carbon of Isatin. Structure of synthesized compounds was elucidated by using IR, 1H NMR & 13C NMR spectrometry. Synthesised compounds showed significant antibacterial activity against E.coli (ATCC 35218), S.aureus (ATCC 25323), E.faecalis (Clinical isolate), K. Pneumonia, P. aeruginosa (ATCC 27893) using agar well diffusion method.

Keywords: Indole, Triazole, nucleophilic substitution, Antibacterial activity.