Tetragonal BaTiO3 particles less than 50nm in diameter have been produced by the gas evaporation method. The conventional gas evaporation of a powder of mixed TiO2 and BaCO3 and the gas flush evaporation of BaTiO3 powders have been performed. In the case of the evaporation of the mixed powder, the crystallization from the amorphous particles was observed. The preparation of a large amount of 20-nm-diameter BaTiO3; particles was achieved by the gas flush evaporation method. These particles showed the characteristic absorption at IS and 23 fun, which can be used for the identification of BaTiO3 nanoparticles. The nanosize particles also showed the characteristic absorption at 320 run in the ultraviolet region. (c), 2005 Elsevier B.V. All rights reserved.