The CeO2 sintering and grain growth kinetics were determined from in situ experiments performed using an environmental scanning electron microscope (ESEM) equipped with a hot stage in the temperature range 1000°C–1300°C. Videos were recorded during 8 h at various holding temperatures where the grain growth and grain elimination process were clearly observed at the grain scale with a 2–10 nm resolution. Data were extracted at both sample and grain scales to characterize the microstructural evolution (grain growth and grain elimination). The grain growth kinetic was described using a parabolic law. The activation energy determined using this method for pure CeO2 grain growth (290 ± 40 kJ/mol) was in good agreement with that obtained using the Dorn's method based on dilatometric measurements (330 ± 30 kJ/mol). The microstructural modifications observed using the in situ HT-ESEM experimental method were compared with computed simulations and revealed a good correlation between the experimental data and the models previously developed.