Abstract: Embodiments of the present disclosure relate to a method of producing a rare earth trifluoride. In the method, a rare earth sulfate or oxalate or rare earth salt (halide) is reacted with a fluoride salt or metal rare earth fluoride to produce the rare earth trifluoride. The reaction is performed at a temperature of 100° C. or less and without using hydrofluoric acid and without producing hydrofluoric acid. Advantageously, the rare earth trifluoride does not evolve hydrofluoric acid when heated between room temperature and 1000° C. Additionally, the product of the reaction includes a major phase of the rare earth trifluoride, and at least 98 wt % of rare earth metal in the rare earth feedstock is converted to rare earth fluoride.