Several crystalline metal phosphites and related hybrid framework solids were prepared under ionothermal conditions using ionic liquids as the reactant, templating agent, and solvent. These compounds display different structures and some appealing properties such as proton conduction. A variety of ionic liquids, metal ions, and additional synthetic variants (e.g., F- and organic ligands) can be introduced into the metal phosphite systems, demonstrating the versatility of the synthetic strategy.