[Display omitted] • The catalytic cycle of H 2 oxidation on lanthanide doped CeO 2 (1 1 1) is proposed. • The presence of oxygen vacancy reduces the catalytic activity for H 2 oxidation. • Lanthanide doping promotes each elementary step in the catalytic cycle. • Sm-doped ceria performs best, consistent with the experimental observations. Lanthanide-doped ceria is known to be a promising solid-oxide-fuel-cell (SOFC) anode material. Understanding the catalytic cycle of fuel oxidation reaction on lanthanide-doped ceria is of great significance for the design of CeO 2 -based anode materials and catalytic processes with improved activity. Herein, we performed density functional theory (DFT) calculations on pure and Pr-, Nd-, Sm-, Gd-doped CeO 2 (1 1 1) to investigate the catalytic cycle of oxygen vacancy (O v) generation and recovery in H 2 oxidation process. Lanthanide doping promotes H 2 dissociation, H 2 O formation, H 2 O desorption, and bulk O2− diffusion steps in the catalytic cycle. On the basis of thermodynamic and kinetic analysis, we propose that under anodic SOFC conditions, there is not a single stable O v on pure, Pr-, Nd-, and Sm-doped surfaces because the first nearest-neighbor O v is filled immediately upon formation, followed by the next catalytic cycle, while one O v exists stably on Gd-doped surface, and subsequent catalytic cycle proceeds on the second nearest-neighbor vacancy site. The presence of a single O v reduces the catalytic activity for H 2 oxidation reactions on Gd-doped surface. Sm-doped ceria showed the best promotion effect for the whole O v -related catalytic cycle, in agreement with the experimental observations. [ABSTRACT FROM AUTHOR]