Three novel isostructural complexes M(gatx) 2 (H 2 O) 2 •4H 2 O [gatx＝gatifloxacin, M＝Zn (1), Ni (2) and Co (3)] were synthesized at room temperature and structurally characterized by elemental analysis, IR and single crystal X-ray diffraction, which exhibit a similar mononuclear structure, in which the metal ion is coordinated by two gatifloxacin and two aqua ligands to furnish a distorted octahedral geometry, and show different activities against staphylococcus due to the different metal ions in the structures.