The feasibility of using plutonium as a fuel in a molten salt reactor has been evaluated by the determination of the solubility of PuF3 in a number of salt compositions containing LiF, BeF2, and ThF4 in the temperature range of interest for such a reactor. An empirical correlation for the solubility of PuF3 as a function of salt composition has been obtained from the solubility data to calculate the solubility of PuF3 in other salt compositions of interest. These data indicate that PuF3 has adequate solubility in salt compositions of interest for a molten salt reactor of either the converter or the breeder type.