Spherical particles of titanium dioxide, anatase, were prepared in a supercritical carbon dioxide medium from titanium alkoxides and water, The dissolution of the alkoxide and stabilization of water dispersions in supercritical CO2 were found to be required for the formation of spherical particles, An anionic fluorinated surfactant was used to stabilize water dispersions in supercritical CO2. This could not be realized with hydrocarbon-based surfactants. The solubility of titanium alkoxides in CO2 appears to parallel their vapor pressure which is dependent on the oligomerization of the unhydrolyzed all;oxides. The polydispersity in particle sizes is due to nucleation occurring simultaneously with particle growth, owing to changes in the degree of supersaturation during the transition from the liquid to I-he supercritical state.