In this study, a novel 1-Phenyl-N-[(1E,2E)-3-Phenylprop-2-en-1-ylidene]Methanamine Schiff base ligand as well as its complexes with copper(II),nickel(II),Iron(II),cerium(III) and gadolinium(IV) metals were synthesized using trans-3-Phenyl-2-Propenal and α-AminoTulene as starting materials in acid medium which was followed by complexation reaction. Both the ligand and metal complexes were characterized by using spectroscopic techniques. The bio-activity of the metal complexes were assay on micro-organisms such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhii, Aspergillus niger and Candida albicans to ascertain its anti-microbial effects by varying the concentration of the metal complexes. Analysis of variance (ANOVA) was used to determine the effects of varying the concentration of the complexes on the microbial activity and on the measured zone of inhibition. Experimental results reveal that the first row transition metals under study: CU2+, Fe2+, Ni2+ are all significant at 5% level of significance while the lanthanides: Ce3+ and Gd4+ are not. An Increase in concentration of Cu2+, Fe2+ and Ce3+ complexes produced a corresponding increase in antimicrobial activity. Varying the concentration of Ni complex has no significant effect as the complex destroys completely the organisms at all levels of concentration while Gd4+ complex show little antimicrobial effect on tested organisms at varying concentration.