A series of complexes of Cu(II), Ni(II), Co(II), Mn(II) and Cd(II) with Isonicotinoylhydrazone-4-diphenylaminobenzaldehyde (INHDAB) has been reported. The complexes have been characterized by analytical data, IR, UV-Vis, NMR spectra, magnetic susceptibility values, thermal analysis and for the Cu(II) complex the ESR spectrum has been registered. The biological activity of these complexes were investigated against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis and Shigella flexneri bacteria. The INHDAB ligand is coordinate at the metallic ions by oxygen amide (O=C) and the azomethine nitrogen.