The reaction of potassiumtetrachloroplatinate with 2-aminothiophenol, yielded a dark blue solid product. This work is about the characterization of this dark blue solid and the investigation of its binding interaction to DNA and enzyme activity. The blue solid product or the &ldquo / blue complex&rdquo / (as we called it in this work) is soluble in acetone, acetonitrile and DMSO yielding a blue solution. It is stable in solution and has a very strong absorption band at 724 nm. The product is paramagnetic and displays one kind of platinum in XPS (platinum binding energies were obtained at 71.1 and 74.6 eV, respectively). The elemental (C, H, N, S, Pt) analysis indicated that the platinum to ligand (2- aminothiophenolate) mole ratio is 1:2. The interpretation of the data collected from elemental analysis and ESR, XPS, NMR, CV measurements leads to conclude that the blue complex prepared in this work is a new platinum blues. This is the first example of platinum blues, in which the bridging ligand is a nitrogen and sulfur donor one. The proposed structure can be visualized as a dimer of binuclear head-tohead isomer of the green product, with C2h symmetry. The band at 724 nm is assigned to an allowed electronic transition from a metal-5dz orbitals based MO to metal-6pz orbitals based MO in tetranuclear core. In order to determine the binding mode of the blue complex to ct-DNA, electronic absorption spectroscopy is employed and hyperchromism about 17.5 percent is observed, which indicates a weak binding of the blue complex to DNA, such as electrostatic interaction of metal ions or H-bonding through the hydroxyl group of the complex. Voltammetric titration carried out in solution suggested the preferential stabilization of Pt(III) to Pt(II) on binding to DNA. The blue complex inhibits the GSTs activity between 45-200 micromolar, in sheep liver GST enzyme. The GST enzymes causes drug resistance, therefore inhibition of this enzyme suggests that this complex can be used in combined chemotherapy.