The present review work is devoted to potentiometric sensors based on high-temperature proton conducting ceramic materials. The technology developments and possible application of such sensors for the determination of concentration of hydrogen-containing components in gases, solids and melts are described and thoroughly discussed. A special attention is devoted to the analysis of experimental data already appeared in international literature and their adequacy to the basic operation principles. On the base of this analysis, the existing problems and future trends are revealed and discussed. (C) 2017 Elsevier B.V. All rights reserved.