The unsymmetric tetradentate Schiff-base, derived from condensation of 2-hydroxy-4­methoxyacetophenone, ethylenediamine and 2,4-pentanedione and its VO(IV), Co(II), Ni(II) and Cu(II) complexes have been isolated. Their mixed-ligand analogs are obtained by reacting these M(II) Schiff-base complexes with triphenyl phosphine in the ratio 1:1. The ligand was analyzed pure by microanalysis and characterized by ¹Hnmr spectroscopy. The metal complexes were characterized by conductance, magnetic susceptibility, infrared and electronic spectral measurements. The ligand coordinates using azomethine N and phenolic O atums to give 4-coordinate square-planar/tetrahedral geometry to Ni(II), Cu(II) / Co(II), 5-coordinate, square-pyramidal geometry to VO(IV) Schiff base complexes and a 6-coordinate, octahedral geometry to the mixed-ligand complexes with water coordinating to the 6^th position in some of them, as corroborated by magnetic moments, IR and electronic spectral data. The antibacterial activity of ligand and all metal complexes against Escherichia coli, Shigella flexneri, Salmonella typhi, Staphylococcus aureus and Bacillus subtilis are generally good. The mixed-ligand complexes are mostly more effective than the precursor metal(II) Schiff base complexes, which are in turn more effective than the ligand against the bacteria used with exception of Shigella flexneri.