A novel series of compounds were synthesized by cyclic condensation reaction of substituted isothiocyanate (2a-c) with 2-thiophenecarboxylic acid hydrazide (1) in the presence of ethyl alcohol, to obtain intermediate thiosemicarbazides (3a-c), which were further treated with sodium hydroxide in the presence of ethanol to obtain triazole derivatives (4a-c). The latter were refluxed with substituted secondary amines and formaldehyde for 6-10 h to afford Mannich bases (5a-k). The synthesized compounds were characterized on the basis of their spectral (IR, (13)C and (1)H NMR) data and evaluated for biological activities. Some of the compounds were found to exhibit significant antimicrobial and antioxidant activity.