Four novel ternary cobalt(II) complexes of the composition [CoLX] where X = 1,10 phenonthroline, L= 2-{[(4-oxo- 4H-chromen-3-yl)methylene]amino}benzoic acid (CMABA), 4-chloro-2-{[(4-oxo-4H-chromen-3-yl)methylene] amino}benzoic acid (CCMABA), 5-nitro-2-{[(4-oxo-4H-chromen-3-yl)methylene]amino}benzoic acid (NCMABA) and N'-[(4-oxo-4H-chromen-3-yl)methylene] benzohydrazide (CMBH) were synthesized and characterized by using elemental analysis, FT-IR, UV-Vis, ESI-MS, molar conductance, thermal analysis(TG,DTA) and magnetic susceptibility measurements. The metal to ligand stoichiometry in all the complexes is 1:1:1. The complexes of CMABA, CCMABA and NCMABA are non-electrolytes; the complex of CMBH is 1:1 electrolyte in DMSO. CMABA, CCMABA and NCMABA act as mononegative, tridentate ligands coordinating through nitrogen of azomethine, oxygen of chromone-carbonyl and oxygen of carboxylic group. CMBH act as neutral, tridentate ligand, coordinating through nitrogen of azomethine, oxygen of chromone-carbonyl and oxygen of benzoyl group. 1, 10- phenanthroline acts as neutral bidentate ligand and coordinating through two nitrogen atoms. All these complexes are paramagnetic to the extent of one unpaired electron. Thermal analysis indicates the presence of coordinated water molecule in all the complexes. Based on analytical, conductance, magnetic, thermal and electronic spectral data, all complexes are assigned octahedral geometry. DNA cleavage studies shows that Co(II) complexes cleave DNA. The biological activity of the ligand and its complexes have been studied on four bacteria E.coli, B.subtilis, Pseudomonas and Edwardella and two fungi penicillium and trichoderma by well disc and fusion method and found that the ternary metal complexes are more active than the free Schiff base ligand.