Metal complexes of the type, [MoO(NCS)4 L-L] (where L-L are amine substituted biologically active Schiff bases with general formula , R1N = CHR2. Here R1 is 4-aminosalicylic acid & R2 is 4-chloro-benzaldehyde, 2-chloro-benzaldehyde, salicyladehyde , vanillin and benzaldehyde) have been prepared by reaction of ammonium tetra-isothiocyanato-oxomolybdate (VI) with the corresponding ligand in aqueous medium in the presence of hydrochloric acid. The complexes have been characterized by elemental analysis, molar conductivity, magnetic susceptibility, infrared spectroscopy and 1HNMR spectroscopy. The metal complexes have been screened against different bacteria for their biological activities. The metal complexes show more potent biological activities as compared with Schiff base ligands.