This paper describes technological challenges in the application of proton conducting ceramics developed in our laboratory. The proton conducting ceramics used here were perovskite-type oxide solid solutions based on cerate or zirconate. Galvanic cell type sensors for detecting hydrogen and other hydrogen-containing compounds could be fabricated using this kind of ceramics. Laboratory-scale hydrogen fuel cells, steam electrolyzers for hydrogen production, hydrogen extractors from gas mixtures and membrane reactors for organic compound gases were made by way of experiment using the ceramics as a solid electrolyte, and they were positively verified to work.