The experimental variations of the rate of crystallite growth in ceria at 943 K are reported as a function of the content (≤10 at %) in foreign cations or additives such as Mg2⁺, Al3⁺, Y3⁺, and Si4⁺ ions. The process of surface area decrease due to crystallite growth is described by a kinetic model involving oxygen and cerium ions diffusion. From the calculation of the concentration in oxygen vacancies, electrons and cerium vacancies, the diffusion current can be obtained versus the oxygen partial pressure and the foreign cation concentration. The rate obtained from the model is compared to the experimental one.