Five cationic platinum(II) complexes of general formula, [Pt(NH(3))(2)(β-diketonate)]X are reported, where X is a noncoordinating anion and β-diketonate = acetylacetonate (acac), 1,1,1,-trifluoroacetylacetonate (tfac), benzoylacetonate (bzac), 4,4,4-trifluorobenzoylacetonate (tfbz), or dibenzoylmethide (dbm), corresponding, respectively, to complexes 1-5. The log P values and the stabilities of 1-5 in aqueous solution were evaluated. The phenyl ring substituents of 3-5 increase the lipophilicity of the resulting complexes, whereas the trifluoromethyl groups of 2 and 4 decrease the stability of the complexes in aqueous solution. The uptake of 1-5 in HeLa cells increases as the lipophilicity of the investigated complex increases. Cancer cell cytotoxicity studies indicate that 1 and 3 are the least active complexes whereas 2, 4, and 5 are comparable in activity to cisplatin.