Vacuum distillation methods were demonstrated to be effective for producing high‐purity crystals of LiF. It was established from chemical analyses of condensate products that under the experimental conditions adopted, 995°C and 4 to 5×10−2Torr, the order of vaporization for the fluorides, NaF, MnF2, LiF, MgF2, and CaF2, corresponds to the order of their decreasing vapor pressures. Under similar experimental conditions LiF containing no more than 200 ppm of oxygen could be produced from mixtures of LiF and Li2O.