An electrolytic perovskite and method for synthesizing the electrolytic perovskite are described herein. Basically, the electrolytic perovskite is a solid that has an ion conductivity greater than 10.sup.-5 S/cm in a temperature range of 0 400.degree. C., wherein the ion is Li.sup.+, H.sup.+, Cu.sup.+, Ag.sup.+, Na.sup.+ or Mg.sup.2+. For example, Li.sub.1/8Na.sub.3/8La.sub.1/4Zr.sub.1/4Nb.sub.3/4O.sub.3 (5.26.times.10.sup.-4 S/cm) and Li.sub.1/8K.sub.1/2La.sub.1/8NbO.sub.3 (2.86.times.10.sup.-3 S/cm) are two electrolytic perovskites that have been synthesized in accordance with the present invention that have a high Li.sup.+ conductivity at 20.degree. C. Both compositions have been confirmed in experiments to conduct Ag.sup.+ and H.sup.+ ions, as well. The present invention also includes a solid proton conductor that can be formed from the electrolytic perovskite by replacing the ions located therein with protons. The electrolytic perovskite and solid proton conductor can be used in a wide variety of applications or devices including, for example, a fuel cell, a membrane reactor, an amperometric hydrocarbon sensor or a steam electrolysis application.
