SAA (supercritical assisted atomization) process until now has been successfully tested on various compounds using a laboratory scale apparatus. In this work scale-up of the process has been performed, based on the geometrical similitude, the same Reynolds and Weber numbers in the nozzle and the same residence time in the saturator. Experiments have been performed on both laboratory and pilot plant to compare the process performance using zyrconil nitrate hydrate in water and rifampicin in methanol as model compounds. Depending on the concentration, amorphous spherical particles of zyrconil nitrate hydrate with modes ranging between 0.3 and 0.7 mu m and of rifampicin ranging between 0.3 and 0.4 mu m, have been obtained with small differences between the two apparatuses demonstrating that SAA is a stable, flexible and easily scalable process. (c) 2006 Elsevier B.V. All rights reserved.