text: Rare earth oxides exhibit intrinsic hydrophobicity, and hence can be used in thermally stable heat exchangers and other applications involving high-temperature hydrophobicity. The presence of oxygen vacancies at surfaces of ceria or other rare earth oxides is instrumental in governing surface wettability. Adsorption of water at oxide surfaces can occur as molecular adsorption, in which HO molecules remain intact at the terminated surface, or as dissociative adsorption, in which OH and H are adsorbed separately at solid surfaces. The presence of oxygen vacancies is generally found to enhance hydrophobicity while promoting dissociative adsorption.