Oxides that exhibit significant proton conductivity at elevated temperatures are candidates for different electrochemical applications, such as hydrogen sensors, membranes for hydrogen production, and proton conducting ceramic solid oxide fuel cells (PCC-SOFC). The most studied ceramic proton conductors are those based on Ba(Zr/Ce)O3 with the perovskite structure. However, these materials show several drawbacks (CO2 stability/sintering issues) for practical applications. Alternative proton-conducting materials with non perovskite-based structures are therefore being sought to overcome these drawbacks. In addition, there is a need to develop materials showing mixed proton/electronic conduction for use as electrodes in PCC-SOFCs and as hydrogen separation membranes. This proposal is targeted at two new proton conducting systems/structure-types.