Particle size is a key factor for the performance in the use of different organic and inorganic materials. The first observation on the possibility of obtaining ultrafine powders through supercritical fluid (SF) processing was made in 1876 (1 ), but not until 1984 did Krukonis (2 ) demonstrate the potential of SFs for processing a variety of solids that are difficult to comminute. The great advantage of using SFs is in the possibility of producing solid phases with unique morphology at mild operating conditions.