Abstract The outstanding properties of cerium oxide from its capacity to transit from Ce3+ to Ce4+ (and from Ce4+ to Ce3+) make it very useful for a wide range of technological applications of great importance. We performed experiments sending pulses of CO that interact with the surface of nano cubes of CeO2 with low index faces (100). We model this process through the statistical description of the creation of oxygen vacancies leading to the appearance of Ce2O3. The model is able to predict the composition of the equilibrium nano cubes surface under different experimental conditions. The theoretical results are compared with the obtained experimental values of CO consumption, which is related to the presence of Ce3+ atoms.