To alleviate the alarming problem of microbial resistance to antibiotics transition metalcomplexes are taken as alternatives. In line with this, in this work, two complexesofcobalt(II)namely,[Co(Bpy)2(H2O)]Cl2and[Co(Bpy)2(Ad)(H2O)]Cl2were synthesizedfrom4,4’-bipyridine alone as well as from both 4,4’-bipyridineand adenine. The synthesis was checked using halide test, conductance measurement, and spectroscopic (ICP-OES, FTIR, and UV/Vis) analysis. Their in vitro antibacterial activities werealso investigated on two Gram-positive Staphylococcus aureus (S. aureus) and Streptococci pyogens (S.pyogens) and two Gram-negative (Escherichia coli (E. coli) and Klebsiella pneumonia (K. pneumonia)) bacteria.These complexes showedwide-range activities against even themost drug resistant Klebsiella pneumonia(K. pneumoniae). [Co (bpy)2(H2O)]2Cl2inhibited S. aureus,S.pyogens,E. coliandK. pneumoniaeby -27.7%,-42.54%-58.6% and-33%, respectively, compared to gentamicin. Similarly,[Co (Bpy)2(Ad)(H2O)]Cl2inhibited these pathogens by -20.55,-39.3%,-30% and -69%respectivelycomparedtogentamicin.Therefore, anti-bacterial studies of the complex against four bacteria pathogens found to be higher inhibition towards to Staphylococcus aurous, Streptococci pyogens and Klebsiella pneumoniabut [Co(Bpy)2(Ad)(H2O)]Cl2 lower antibacterial activity towards against Escherichia coli. Thus after in vivo cytotoxicity investigations, these compounds can be considered as potential antibiotic drug.