The behavior of potential ceramic materials (electrolytes conducting on oxygen ions) of electrochemical control devices of technological operations in oxide-halide melts was investigated.Based on the literature data and thermodynamic estimates for long-term tests in the LiCl, LiCl-Li2O and LiCl-Li2O-Li melts at a temperature of 650 °C, mixtures of oxides ZrO2-Y2O3 (YSZ), ZrO2-Sc2O3 (ScSZ), ZrO2-CaO (CaSZ) and CeO2-Gd2O3 (CGO) were selected.These melt under the studies are the most widely used in a number of high-temperature electrochemical processes of obtaining metals and alloys, as well as in the developed schemes of pyrochemical processing of nuclear fuel.The stability of the samples was determined by changes in mass, appearance, elemental analysis of the melt, as well as via the scanning electron microscopy. According to the results of resource tests in the LiCl-Li2O melts, it is shown that the ZrO2-Sc2O3 sample is thermally unstable (destroyed), and cerium in the CeO2-Gd2O3sample partially changes the oxidation degree to III, that does not allow it to be used as a material conducting only on oxygen ions.The best stability in LiCl-Li2O melts was shown by the samples of ZrO2-Y2O3 with cubic and tetragonal structures and the samples of ZrO2-CaO. Based on the changes in the microstructure of the samples, it was concluded that the increase in the content of Li2O in the LiCl-Li2O melt accelerates the destruction of the sample mainly by the mechanism of dyeing, and the presence of lithium leads to loosening of the samples. Both factors (an increase in the content of Li2O and the appearance of lithium in the melt) accelerate the destruction of samples, reducing the endurance of the electrochemical devices duringthe direct contact of ceramic materials ZrO2-Y2O3, ZrO2-Sc2O3 with the studied melts.