The study of the coordination chemistry of biologically important metal ions with mixed heterocyclic ligands have gained importance. The increase in the mortality rate caused by drug resistant bacteria has been the concern of researchers in inorganic medicine and pharmaceuticals. The discovery of novel active compounds against new targets is a matter of urgency. Based on this, we report two new mixed ligand complexes of cobalt (II) homobinuclear and mononuclear, which were synthesized from CoCl2.6H2O, 1,10-phenanthroline monohydrate, and ethylenediamine. These complexes were characterized using spectroscopic (ICP-OES, FT-IR, and UV-Vis), chloride determination as well as melting point and conductance measurement. In vitroantibacterial activity was also tested on two Gram positive (S. aureus, S. pyogenes) and two Gram negative (E. coli and K. pneumoniae) bacteria using disc diffusion method. The complexes performed well even against the Gram-negative bacteria. The antibacterial result was found comparable with the commercial drug Gentamicin even at lower concentration of complexes. Thus, the synthesized complexes may be considered as potential antibacterial agents after passing cytotoxicity testing. Keywords: Mixed mono and binuclear cobalt (II) complexes, Spectroscopic studies, Antibacterial activity