A novel series of complexes of the type [M (C18H17N2O2Cl)2], where M= Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ), Zn(Ⅱ) and Mn(Ⅱ) and C18H17N2O2Cl correspond to the bidentate ligands, were synthesized, and characterized by UV-Vis, FTIR, and Mass spectroscopies. The bidentate ligand was synthesized in a typical one-pot, three-component condensation of malononitrile, 4-chlorobenzaldehyde, and dimedone in the present of alum as catalyst. The synthesized ligand and its metal complexes were screened for in vitro antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aurous) bacterial strains. The most antibacterial activity of the synthesized compounds belongs to cobalt and copper complexes. The minimal inhibitory concentrations (MICs) against E.Coli and S.aureus were 16 and 32 μg/ml, respectively. The results of these studies showed that the metal complexes have more antibacterial activities as compared with the non-complexes ligand.