The e.m.f.'s of the following solid-electrolyte galvanic cells have been measured over the temperature ranges shown. Cell (1) was studied to check the experimental technique and cell (2) was studied to confirm the absence of electronic conductivity in CaF2-electrolyte at especially small chemical potentials of fluorine. Thermodynamic functions have been derived from the results for the reactions: La + 1.5F2 = LaF3, Y + 1.5F2 = YF3, Sc + 1.5F2 = ScF3, Mn + F2 = MnF2, and Pr+1.5F2 = PrF3.