The technology of H₂ separation is essential for the utilization of hydrogen fuel, which is strongly motivated by the grand challenge of climate change. Electrochemical membrane based on cerate, titanate and zirconate ceramics is a promising technology of H₂ separation. In particular, SrCeO₃ perovskites with mixed protonic and electronic conductivities are promising materials for H₂ separation due to negligible oxygen permeability. However, low electronic conductivity of SrCeO₃ often limits the overall H₂ flux. The increase of electronic conductivity via B-site doping has been largely based on trial-and-error experiments. This lack of understanding limits further design and development of hydrogen membrane materials. In this presentation, we will share our computation studies of revealing distinctive behaviors of different dopants in enhancing electronic conductivity via novel polaron mechanism, using first principles hybrid functional calculations. Our study shows SrCeO₃ can trap excess charge as electron or hole polarons on Ce⁴⁺ or certain dopants. The enhancement of different dopants to electronic conductivity can be determined by the ability of polaron formation and migration. Based on the insight of the polaron enhancement mechanism, new promising dopants are predicted to increase electronic conductivity, and the computation predictions are verified by preliminary experiments. Thus, our study demonstrates first principles techniques in accelerating deign of mixed conductors through tailoring polaron, and provides new avenues for the future design of the materials with different polaronic behavior to achieve improved conductivity and other properties.