The invention relates to a process and an apparatus for producing stably fine-particle powders. The invention starts from a process for producing stably fine-particle powders in which one or more substances A and one or more substances B are dissolved in supercritical fluids, and the solutions are decompressed along a holdup section. In the process, substances A and B are each dissolved in separate supercritical compressible fluids, and the holdup sections interpenetrate, with the solubility limit of A in the appropriate fluid being exceeded at an earlier time than is the solubility limit of B in the appropriate fluid.