The polydentate ligand, 3-[(2-hydroxy-benzylidene)-amino]-2-thioxo-imidazolidin-4-one, was synthesized by intermolecular cyclocondensation reaction of 2-hydroxybenzaldehyde thiosemicarbazone and ethylchloroacetate. Novel palladium(II) complex was obtained by nucleophilic substitution of both DMSO ligands from cis-[Pd(DMSO)2Cl2] with iminic nitrogen and thiolactamic sulfur from ligand. The structure of compounds was characterized on the basis of their spectral data. The cytotoxic activity of the ligand and palladium(II) complex was studied on tumor cell lines: human colon carcinoma HCT-116 and SW-480 cells using MTT viability test. The results show that investigated palladium(II) complex has significantly greater cytotoxic effect compared to ligand. [Projekat Ministarstva nauke Republike SRbije, br. 172011 and III41010