Copper (II), Cobalt (II), Nickel(II) and Mercury(II) Complexes of Rhodanine-3-acetic acid-2- imino thiophenol (RDABT) have been synthesized and characterized by elemental analysis, conductivity, magnetic susceptibility measurements, IR, ESR and electronic spectral data. The molar conductivity data showed as slight ionic nature of the complexes. The tri dentate nature and electronic spectral data suggest that all the metal complexes are square planar geometry. The antimicrobial activities of the ligand and its complexes have been screened and showed in Table-7 &8. Based on the experimental results metal complexes showed more toxic effects than free ligand ( RDABT ). It has been reported that the metal complexes of ligand containing sulphur as a donor atom and electron with drawing group exhibit improved biological activity[1]. It led us to synthesize and characterize the new Schiff base (RDABT) and its complexes.