A fast and efficient synthesis of some 1,4-disubstituted thiosemicarbazide derivatives is described. The reaction of 3-chlorobenzoic acid hydrazide with various aryl isothiocyanates gave thiosemicarbazide derivatives (1–11) in good yield. The cyclization of compounds (1–11) in the presence of 2% NaOH resulted in the formation of compounds (12–22) containing the 1,2,4-triazole ring. A series of new Mannich bases (23–33) related to the structure of 1,2,4-triazole has been also synthesized. All of these compounds were tested for their in vitro antibacterial activity against the reference strains of aerobic bacteria - 6 Gram-positive and 3 Gram-negative ones; 12 Staphylococcus aureus clinical isolates were also examined. An attempt was made to clarify the influence of the nature/position of substituents on antibacterial activity of compounds described. Synthesis and antimicrobial evaluation of some 1,4-disubstituted thiosemicarbazides, s-triazoles and Mannich bases were described. Compounds 4, 6, 15 appeared to be four-fold more effective against Bacillus cereus ATCC 10876 than ampicillin. Display omitted ► Fast and efficient method for the preparation of thiosemicarbazides is described. ► Antimicrobial activity depends on the nature/position of substituents. ► Some derivatives appeared to be more effective than ampicillin