[en] Cerium was used as a surrogate for plutonium in studies of the solubility and precipitation of the trifluoride salt. Cerium trifluoride was precipitated using a two-stage precipitation system. A series of precipitation experiments were used to identify the significant process variables affecting precipitate characteristics. A mathematical precipitation model was developed which is based on the formation of cerium fluoride complexes. The precipitation model relates all process variables, in a single equation, to a single parameter which can be used to control particle characteristics. 11 references, 9 figures, 8 tables