Abstract Mixture of cephalexin (Cep) and amoxicillin (amx) in 1:1 mole ratio, interact with transition metal ions to give [M(cep)(amx)].3H2O complexes in 1:1:1 mole ratio, where M = Co(II), Ni(II), Zn(II) and Fe(III). The complexes were characterized by physicochemical and spectroscopic analysis. The UV/Vis spectral data suggestedan octahedral geometry for Co(II), Ni(II) and Fe(III) structures, while Zn(II) complex adopted tetrahedral geometry. The IR spectral data shows that the ligands coordinated to the metal ion through their v(NH), v(COO) and v(C=O) functional respectively due to the similarity in their structures. The complexes have been screened for antimicrobial activity against different strains of bacteria which includes Gram positive, Gram negetive and fungus, and the results are compared with the activity of the ligands (antibiotics).