presents the synthesis, spectral analysis and antimicrobial evaluation of a new series of substituted 1,2,4-triazole (5a-i) and 1,3,4-thiadiazole derivatives (9a, c, g, h). New compounds were obtained by cyclization reaction of acyl thiosemicarbazide derivatives in the presence of alkaline and acidic media. All synthesized compounds were screened for their in vitroantimicrobialactivities. Nine of the