<p>Synthesis of four new platinum(IV) complexes <strong>C</strong><strong>1–C4</strong>, with bidentate <em>N,N'</em>-ligand precursors, <em>O,O'</em>-dialkyl esters <strong>L1-L4</strong> (alkyl = ethyl, propyl, butyl and pentyl), of (<em>S,S</em>)-ethylenediamine-<em>N,N'</em>-di-2-propanoic acid, H<sub>2</sub>-<em>S,S-</em>eddp were reported. The reported platinum(IV) complexes characterized by elemental analysis and their structures were discussed on the bases of their infrared, <sup>1</sup>H and <sup>13</sup>C NMR spectroscopy. The cytotoxic activity was determined on tumor cell lines: human breast carcinoma MDA-MB-231, human colon carcinoma HCT-116 and SW-480, using MTT test. It showed the greater the size of the investigated complex or ligand the greater the cytotoxicity.</p>