A series of novel complexes of 4-amino-5-benzyl-4H-1,2,4-triazole-3-thione (ABT), 5-benzyl-4-(benzylideneamino)-4H-1,2,4-triazole-3-thione (BBT), 5-benzyl-4-[(2-hydroxybenzylidene)amino]-4H-1,2,4-triazole-3-thione (HBHT) and 5-benzyl-4-[(4-methoxybenzylidene)amino]-4H-1,2,4-triazole-3-thione (BMT) with the divalent ions Co(II), Ni(II), Cu(II) and Cd(II) have been prepared by direct combination of the ligand and metal chloride salt in ethanol. The structures were determined by elemental analysis, molar conductance, magnetic measurements, thermal behaviour, infrared and electronic spectral data. ABT involves N (amino group) and S donor atoms, BBT and BMT involve N (azomethine) and S donor atoms, both act as neutral bidentate ligands. HBHT involves N, O and S donor atoms, acting as monobasic tridentate ligands. The stoichiometry of these complexes is M:L = 1:1 and/or 1:2. The geometry of the complexes was assigned on the basis of magnetic and electronic spectral data. Tetrahedral and octahedral structures were proposed for the metal complexes. The ligands and their complexes were screened for their antibacterial activity.