The additive effect of 31 metals on activity of ceria catalysts was studied for the conversion of ethanol to propene. Yttrium gave the best results and the propene yield showed a volcano-shaped dependence on the Y amount, being maximized at 20 atom% Y to that of Ce. The catalyst was stable due to very small carbon deposition rate which was approximately 1/100 of that on the parent CeO2 catalyst. The water addition increased the propene yield to 30%, decreased the ethene yield to 37%, and did not change the durability. The physicochemical characterization of the Y/CeO2 catalysts indicated that the surface of active catalysts was covered with a solid solution of Ce-2 and Y2O3. Pulse experiments of various candidate compounds suggested that the reaction pathways were ethanol -> acetaldehyde -> ethyl acetate -> acetic acid -> acetone 2-propanol -> propene through Tishchenko reaction, ketonization, and Meerwein-Ponndorf-Verley reduction. (C) 2014 Elsevier Inc. All rights reserved.