Hydrogels obtained from lower toxicity monomers of N-(hydroxymethyl)acrylamide and N, N′-methylenebisacrylamide were applied to form nonstoichiometric CaZrO 3-based electrolytes. A coprecipitation-calcination method with ((NH 4) 2C 2O 4) in concentrated NH 3 aqueous solution was used to synthesise CaZrO 3 involving 51 mol.% CaO (CZ-51) powder. The gas-tight CaZrO 3-based rods were prepared by the gel-casting method with 45 vol.% suspension and then sintered at 1500 °C–2 h. It was found that in low oxygen partial pressure, the nonstoichiometric CaZrO 3 obtained by gel-casting method were pure oxide ion conductors. These samples exhibited comparable electrical conductivity values to isostatically compressed pellets starting from the same powder. The results of experiments on thermochemical stability of CZ-51 gel-cast shapes at high temperatures in air or gas mixtures involving 2–50 vol.% H 2, as well as the corrosion resistance in exhaust gases from a self-ignition engine were also presented and discussed. The thermal resistance of CaZrO 3 obtained rods against molten nickel or iron was also examined. Based upon these investigations, it is evident that only in hydrogen-rich gas atmospheres can the stability of CaZrO 3 shapes be limited due to the presence of CaO precipitation as a second phase. The nonstoichiometric CaZrO 3 (CZ-51) gel-cast materials were also tested in solid galvanic cells, designed to study thermodynamic properties of oxide materials, important for SOFC and energy technology devices. In this way, the Gibbs energy of NiM 2O 4, M = Cr, Fe, at 650–1000 °C was determined. The CaZrO 3 involving 51 mol.% CaO gel-cast sintered shapes seems to be promising solid electrolytes for electrochemical oxygen probes in control of metal processing and thermodynamic studies of materials important for the development of the energy industry.