A series of Co(II) complexes 3 ¢ a-g of 2-(2-chloro-6,7-substituted quinolin-3-yl)-1 H -benzo[ d ]imidazole ligands 3a-g were prepared and characterized by various spectroscopic and physico-chemical methods viz . FT-IR, ESI mass, 1 H NMR, 13 C NMR and UV-Visible spectroscopy, Thermogravimetric analysis, Magnetic susceptibility, Molar conductance and Elemental analysis. The 2-(2-chloro-6,7-substituted quinolin-3-yl)-1 H -benzo[ d ]imidazole ligands 3a-g have been synthesized by cyclocondensation of benzene-1,2-diamine with 2-chloroquinoline-3-carbaldehydes by using ceric ammonium nitrate as a catalyst in presence of hydrogen peroxide as an oxidant. The structures of all ligands were confirmed by IR, Mass, UV-Visible, 1 H NMR and 13 C NMR spectroscopy. All ligands 3a-g and their Co(II) complexes 3 ¢ a-g were screened for their in vitro antimicrobial activity using twofold serial dilution technique against standard MTCC strains of two Gram-positive Staphylococcus aureus and Streptococcus pyogenes , two Gram-negative Escherichia coli and Pseudomonas aeruginosa bacteria and three Candida albicans , Aspergillus niger and Aspergillus clavatus fungus in comparison with standard drugs. All ligands 3a-g and complexes 3 ¢ a-g also evaluated for antimycobacterial activity against standard Mycobacterium tuberculosis H 37 Rv strain. DOI: http://dx.doi.org/10.17807/orbital.v7i2.530