Two new dimeric Zn(II) ([{ZnL(1)(DMSO(2))}(2)]·DMSO (1), [{ZnL(2)Cl}(2)] (2)) and a novel tetrameric Zn(II) complex ([(Zn(2)L(3))(2)(μ-OAc)(2)(μ(3)-O)(2)] (3)), where H(2)L(1) = 4-(p-methoxyphenyl) thiosemicarbazone of o-hydroxynapthaldehyde, HL(2) = 4-(p-methoxyphenyl)thiosemicarbazone of benzoyl pyridine and H(2)L(3) = 4-(p-chlorophenyl)thiosemicarbazone of o-vanillin are reported. Ligands and their complexes were characterized by spectroscopic and single crystal X-ray diffraction techniques. In addition, the complexes exhibited good binding affinity towards HSA (10(12) M(-1)), which is supported by their ability to quench the tryptophan fluorescence emission spectra of HSA. The complexes were also screened for their DNA binding propensity through UV-vis absorption titration, circular dichroism and fluorescence spectral studies. Results show that they effectively interact with CT-DNA through an intercalative mode of binding, with binding constants ranging from 10(3) to 10(4) M(-1). Among the three complexes 1 has the highest binding affinity towards CT-DNA. Further, the phosphatase activity was evaluated using bis(2,4-dinitrophenyl)phosphate (BDNPP) as substrate, however, the complexes did not yield any measurable catalytic activity. Nevertheless the complexes showed significant cytotoxic potential against HeLa and HT-29 cancer cell lines that was assessed through MTT assay and DAPI staining. Remarkably, complex 1 showed better activity than cisplatin against HT-29 cell line.