The lanthanide complex aquatrichloridobis(1,10-phenanthroline)cerium(III) [Ce(phen)(2)(H2O)Cl-3] (KP776) was fully characterized by elemental analysis, IR-, and H-1- and C-13-NMR spectroscopy, as well as TG/DTA measurements, and its behavior in H2O, important for the application as a chemotherapeutic, was studied. In addition, the binding of KP776 to nucleotides and single serum proteins was investigated by capillary electrophoresis, whereas binding to proteins in human plasma was observed by ICP-MS. The compound shows promising anticancer properties in vitro: proliferation of human cancer cell lines is strongly inhibited with IC50 values in the very low micromolar range.