A tridentate Schiff base ligand was synthesized via the reaction of 2-hydroxynpthaldehyd with N-phenyl-o-phenylenediamine. The obtained ligand was utilized in synthesizing Pt-L2 [PtCl(N^N^O)]. The ligand and Pt-L2 were characterized by IR, NMR and mass spectroscopies as well as elemental analysis. The DNA-binding of Pt-L2 was examined by fluorescence quenching using the EB-DNA adduct method. The apparent affinity for the compound toward ct-DNA was nearly twice the affinity of ethidium bromide. Changes in the relative viscosity induced by platinum complexes of ct-DNA indicated an intercalation mode of binding for Pt-L2 and covalent binding for the second platinum compound, Pt-L1, synthesized from 3-ethoxysalicyaldehyde and N-phenyl-o-phenylenediamine. BSA-binding by Pt-L2 indicated the spontaneous formation of an adduct with the protein with good binding affinity (7.7 × 104). The anticancer activities of Pt-L2 were evaluated against two cancer cell lines and compared to that of Pt-L1 and cisplatin. Pt-L2 has better IC50 values, possibly because of its highly π-delocalized planar system. Moreover, selectivity index for Pt-L2 is high (SI = 168) which is one of the criteria for potential chemotherapeutic agents (higher than that observed for cisplatin (SI = 37)).