Molten oxide electrolysisMolten oxide electrolysis (MOE) could enable a low-carbon route for production of technology-critical metalsCritical metals that are required for sustainable energy production. All-oxide MOE doesn’t create toxic halide waste, could use electricity generated from renewable energy sources, and wouldn’t directly produce greenhouse gases if inert anodes can be identified. There are myriad technical challengesChallenges including electrolyte chemistry, conductivity and stability; crucible and electrode stability, conductivity and longevity; and feedstock chemistry. Thermodynamic predictions from CALPHAD provide guidance on optimal chemistry and cell operating conditions, but may not be available for systems and conditions of interest. Here, we discuss progress on selective reduction of candidate metals, titanium and tantalum, by MOE and ways to overcome their specific technical challengesChallenges. Further, we describe a promising new method for determining the electrical conductivityElectrical conductivity of reactive liquids at high temperatures.