The objective of the present study is to prepare a family of new monoanionic tridentate Ceftiofur metal complexes [M(Ceftiofur)Cl].xH2O, where M = Mn(II), Ca(II), Fe(III), Cu(II), Zn(II), Mg(II), Co(II) and Ni(II) and to characterize them by different physiochemical techniques. These Ceftiofur metal complexes are further screened for biological activities. Several physiochemical and spectroscopic methods like UV-Vis, 1 H-NMR, IR, elemental analysis, and Karl-Fischer titration were used to find out the actual stoichiometry and binding mode of these complexes. The complexes synthesized were subjected to anti-microbial activities using gram-positive as well as gram-negative strains. The chosen strains are Staphylococcus aureus (MTCC87), Bacillus subtilis (MTCC441), Escherichia coli (MTCC40), Proteus vulgaris (MTCC426), Pseudomonas aeuruginosa (MTCC2488), Bacillus cerus (MTCC430), Salmonella typhimurium (MTCC1253). The solubility of Ceftiofur hydrochloride was remarkably decreased in most of the commonly used solvents on its complexation with metal ions under study. The stoichiometric study of these synthesized complexes revealed 1:1 ratio of ligand to metal binding. Ceftiofur showed that on complexation the antibacterial study was affected. The Cu 2+ and Co 2+ complexes against Pseudomonas aeuruginosaand Co 2+, Mg 2+ and Ni 2+ complexes againstSalmonella typhimurium showed the highest antibacterial activity, whereas Ca 2+ complex showed the highest activity against Proteus vulgaris. Majority of the bacterial strains were found to be resistant to the complexes of Fe 3+ and Zn 2+ .