Titania powders were synthesized via hydrolysis of titanium(IV) isopropoxide (TIP) in supercritical carbon dioxide (SCCD). Injection of TIP into water-in-CO2 (w/c) dispersions resulted in precipitation of spherical titania particles, and free-flowing white titania powders were isolated in 65-70% yield by slow isothermal depressurization. Qualitatively similar results were obtained with and without the addition of an anionic phosphate fluorosurfactant (DuPont Zonyl FSP) to stabilize the w/c dispersions. The titania powders had broad particle size distributions (20-800 nm) and specific surface areas in the 100-500 m(2)/g range. Addition of Zonyl FSP resulted in a decrease in specific surface area at a given water-to-alkoxide molar ratio (hydrolysis level). The specific surface area increased as the hydrolysis level was increased, irrespective of the presence of surfactant. The surface area is associated primarily with internal-porosity of the spherical titania particles, as evidenced by scanning transmission electron microscopy and N-2 porosimetry. Calcination of a surfactant-free titania powder at 300 C in air decreased the specific surface area from similar to300 to 65 m(2)/g and increased the mean cylindrical pore diameter from 2.6 to 4.9 nm, consistent with collapse of micropores. Titania nanoparticle synthesis via TIP hydrolysis in SCCD was attempted using w/c microemulsions formed with ammonium carboxylate perfluoropolyether (PFPE-NH4); however, injection of TIP into PFPE-NH4-stabilized microemulsions resulted in precipitation of 0.3-2 mum titania particles. The use of other CO2-soluble titanium(IV) alkoxides gave qualitatively similar results.