Ultrafine CeO 2 particles were perpared by sol gel method using citric acid as complex agent. The influence of preparation conditions such as molar ratio of Ce 3+ and citric acid, reaction temperature, pH value, drying temperature of the gel, calcination temperature and time of xerogel on the particle size and specific surface area has been studied in detail. XRD, TEM, DTA and BET surface area measurements were used for the samples characterization. It is found that the molar ratio of Ce 3+ and c...