In this thesis, the synthesis, characterizations (conductivity measurements, melting point determination ,chlorideestimation,FT-IR, UV-Vis, ICP-OES) and biological activities of a new mononuclear copper(II) complex of the type [Cu(phen)2CH3CONH2]2+2Cl-.H2O, where phen=1,10-phenanthroline is described. The in-vitro antimicrobial study result was also compared with the commercially available antimicrobial activities such as, Cotrimoxazole, Penicillin, Tetracycline, ciprofloxacin and Ampicillin as standard antibiotics to determine the antimicrobial activities of the complexes. The synthesized complex demonstrated better activities on staphylococcus aurous and Klebsella pneumonia. Thus, after cytotoxicity investigations, this complex could be considered as an alternative antibiotic agent. Key words: Cu(II)chloride salts, mononuclear complex, antimicrobial activity, 1,10-phenantrolein, acetamide.