A method for producing particles, from a substance, having predetermined size and/or morphology characteristics. The method consists of mixing within a spray nozzle a solution stream containing the substance in dissolved or dispersed form with a supercritical fluid stream. Spraying the mixture through a nozzle into a particle collecting chamber and there separating the particles. The characteristic feature is an additional step, providing a make-up agent (modifier) to the fluid stream, possibly combined with recycling of the fluid and/or performing the method essentially simultaneously in several spray nozzles. Additional features are also a production system comprising functions for performing the method above and the introduction of the make-up agent, recycling of the fluid and performing several runs essentially simultaneously in the same production system. Also a pharmaceutical formulation in which particles produced according to the method has been used for its manufacture.