Supercritical Assisted Atomization (SAA) was used to micronize poly(methyl methacrylate) (PMMA) and poly-L-lactide (PLLA), selected as a model polymers, to verify SAA processability of polymers and the performance of this process. The effect of process parameters such as the mass flow ratio between carbon dioxide and liquid solution, precipitation temperature and solute concentration in the liquid solution were studied to evaluate their influence on morphology and size of precipitated particles. Successful micronization of the polymers was obtained with a narrow particle size distribution. PMMA and PLLA size-controlled microparticles were produced ranging between 0.05 and 1.6 mu m and between 0.1 and 3.5 mu m, respectively. Both PMMA and PLLA presented a good processability at temperature conditions far from the glass transition temperature, but high enough to allow a fast solvent evaporation. (C) 2006 Elsevier B.V. All rights reserved.