Investigations on the Chlorine Evolution at CeO2-Modified RuO2/TiO2 Anodes.-Electrochemical measurements in Cl2-saturated 4 M NaCl solution ( current density-potential and potential-decay curves) at modified RuO2/ TiO2 anodes show that the addition of small amounts of CeO2 to the active anode material significantly enhances the electrochemical activity for the chlorine evolution reaction, which is explained by an increase in the number of electrocatalytic surface sites. The potential-decay curves of anodes containing 0.25-0.5 mol% CeO2 indicate a transport-limited process. The rate-determining step is the removal of gaseous Cl2 from the electrode surface. -(KUEHNEMUND, L.; HEIDRICH, H.-J.; SABELA, R.; STEPAN, L.; MUELLER, L.; Z. Phys. Chem. (Leipzig) 271 (1990) 5, 901-909; Sekt. Chem., Humboldt-Univ. Berlin, O-1080 Berlin, Fed. Rep. Ger.; DE)