A major problem of medical world is faced with the rapid development of resistance to the existing antimicrobial drugs, which needs the discovery of new antimicrobial compounds. Considerable attention has been focused on mixed-ligand with transition metallic ions which drive to obtain new compounds with a wide range of biological properties, having a good reactivity and stability [1]. New mixed-ligand Co(II) and Ni(II) complexes with enrofloxacin and 1,10phenanthroline/8-hydroxyquinoline have been synthetized. The metal complexes have been characterized by elemental analyses, molar conductance, FTIR, solid reflectance, magnetic moment, thermal analyses, X-ray powder diffraction and SEM analysis. Conductance measurements indicate that all the complexes are nonelectrolytes. Spectral data showed that the deprotonated enrofloxacin is bidentately bound to the metal ion through the pyridone oxygen and a carboxylato oxygen; 1,10phenanthroline acts as neutral bidentate ligand coordinated through two nitrogen donor atoms and the deprotonated 8-hydroxyquinoline is coordinated through nitrogen and oxygen donor atoms [2]. The geometry of the complexes was elucidated with solid reflectance UV and magnetic moments. TG experiments revealed the thermal stability of metal complexes and confirmed their compositions suggested by the analytical data. In addition to experimental data molecular modeling study has been made and present the optimized geometries of metal complexes. The powder XRD and SEM studies show that all the complexes are nanocrystalline.The metal complexes were investigated in vitro for the cytotoxic assay.