Abstract: A process for the growth of new, and difficult-to-synthesize, metal oxide, and other mixed anion oxide-based, single crystals from a molten metal flux. Metal fluxes are new for the growth of metal oxide single crystals. Preliminary reactions proved that new phases and phases that normally require costly, extreme conditions do grow as single crystals. Batches of individual reactions are heat-treated to synthesize single crystals comprised of oxygen with one or more transition, alkaline-earth and/or lanthanide metals, and can also include other anions like chalcogens or pnictogens, or halides. The reactivity and the propensity for crystallization of charge compensated single crystals from alkaline earth fluxes have been made evident by the results presented here.