The electrochemical behavior of the LaF₃ : Eu²⁺|Me interface (Me = Sm, Ce, Gd, V, Ag) is studied using stripping voltammetry. Current-voltage curves for cells Ag, AgCl|KCl and KF|LaF₃ : Eu ²⁺|Sm (or Ce) may be viewed as background curves for analyzing solid-phase reactions with other metallic electrodes. The substrate material is found to affect properties of interfaces LaF₃ : Eu²⁺/Gd (or V), which are characterized either by solid-phase reactions involving the fluoride ion of a solid electrolyte or by reactions involving oxygen. Regularities, obtained for silver in contact with LaF₃ : Eu ²⁺, link electrochemical signals of the reaction of the silver fluoride formation with the contact area.