In order to elucidate the pyrolysis process, in which droplets of cerium nitrate solution are altered upon denigration into cerium dioxide particles, the effects of the temperature of the surround-ing air, and the initial cerium concentration and normality, upon the droplet temperature, shape, composition, internal and external shape of produced particle and rate of reaction were examined. The pyrolysis process of the cerium nitrate droplet was categorized into four phases : evaporation, foaming, formation of the solid phase and pyrolysis. Correspondence between the time series of the droplet temperature, shape and composition was well recognized. Therefore, it might be possible to understand the dynamics of the pyrolysis process through measurement of the droplet temperature. Furthermore, with increase of the initial cerium concentration, the heating rate of droplet tempera-ture showed sharp, the foaming period and the formation solid-phase period became shorter, and the produced particle was composed mostly of cerium dioxide when the air temperature was above about 600K, resulting in well-crystallized particles. Under about the air temperature, the reactions were moderate, the reaction rate was low and the particle composition included water and nitrate.
