In this study, a series of 1,2,4-triazol-3-carbohydrazide derivatives and compound of 1,2,4-triazole-3-(4H)-thion have been synthesized. Structures and purity of the new compounds were confirmed by the use of their chromatographic and spectral data besides microanalysis. Four different bacterial stains for the study of the biological activity of compounds 6g, 7c, 7g and 7i; two Gram-positive strains, and two Gram-negative strains have been used. Compound 6g was found to be the most active of the four tested compounds against Pseudomonas aeruginosa, Bacillus cereus and Staphylococcus aureus, with an inhibition zone diameter of 16, 9, and 10 mm, respectively. Calculating the minimal inhibitory concentration value (MIC) for the positive drugs who formed an inhibition zone in the agar well diffusion method, we found that both compounds 6g and 7i were the most active of the four tested compounds against Pseudomonas aeruginosa and Bacillus cereus with an MIC value of 0.5 µg/mL for both bacteria. These results suggest that these two compounds could be considered as potential antibacterial agents against a range of bacteria.