Some new ternary complexes of Co(II) with 2-mercapto benzoxazole, 2-amino benzothiazole and 2-(4´- aminophenyl)-6-methyl benzothiazole and with some amino acids (Leucine, Isoleucine) were synthesized and characterized by elemental analysis, IR, 1H NMR spectral studies. The antibacterial activity of these metal complexes has been evaluated against pathogenic bacteria Staphylococcus aureus (+ve) and Escherichia coli (-ve). The antifungal activity of these metal complexes has been evaluated against pathogenic fungi Aspergillus niger and Fusariumoxy sporium. The results indicate that the metal complexes are found more active than the parent ligands.