Electrochemical ceramic membrane reactors (ECMRs) with their unique ability to efficiently couple electrical, chemical, and thermal energy sectors can be a large part of the transition toward renewable energies and defossilized economies. ECMRs utilize ceramic conductors to extract or distribute oxide ions or protons-directly controlled by an external electric current. This article gives an overview of ECMR properties along with the functionalities and advantages. For many reactions, e.g., the direct synthesis of ammonia, ECMRs are not available at the preferred temperature range of 300-550 degrees C. To evidence the possibility of such reactors, functional materials are reviewed. A simple thermodynamic methodology is proposed to determine the suitability of reactions for particular combinations of coupled energy sectors.