Spherical and nonagglomerated Ta2O5 particles of controlled and narrow size distribution have been prepared by vapor-phase hydrolysis of a liquid tantalum pentaethoxide aerosol. Just after the elaboration process, the particles obtained are amorphous and their chemical composition can be expressed as Ta2O5 . (n H2O, n’OH, n"OEt), where n is assigned to the solvation water, n’ to the water issued from condensation of Ta-OH groups, and n" to ethoxy groups resulting from condensation of unreacted Ta-OEt groups. From a microstructural point of view, each particle is constituted of a porous core surrounded by a dense shell with a very smooth surface. Heat treatment at 850-degrees-C leads to the release of water and alcohol and induces the crystallization of the hexagonal beta-Ta2O5 form. The spongelike structure transforms into small crystallites, whereas the outer shell converts into juxtaposed monocrystalline domains; i.e., each particle becomes polycrystalline. The spherical shape is retained upon heating but a decrease in particle size is observed. Increasing the temperature from 850 to 1250-degrees-C induces sintering between the crystallites, and large intragranular pores can appear inside the particles. As the temperature increases, the internal porosity is eliminated, causing some modifications in particle shape. In particular, the smooth surface of freshly prepared particles is not maintained as shown by the emergence of a markedly granular surface state.