A series of mixed-ligand complexes were prepared by reacting by a new primary imidazole azo ligand (4MCFD) and 1,10-phenanthroline as a secondary ligand with divalent ions of cobalt, nickel, mercury, and cadmium, yielding complexes with the general formula [M (4MCFD) (1,10-phen) Cl₂]. The synthesized complexes were characterized using C.H.N. analysis, atomic absorption, FT-IR, UV-Vis, magnetic susceptibility, and molar conductivity. The stability constant (K_Stability) values and the effect of time at 25°C indicated high stability for these complexes. An octahedral geometry was suggested for all complexes, with both primary and secondary ligands acting as bidentate. The inhibition ability of the free ligands at 50 mg/mL in DMSO was found to be lower than that of the complexes against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa.