Layered double hydroxide (LDH) nanosheets have exceptionally high hydroxyl ion (OH–) conductivity (as high as 10-1 S/cm), report investigators. This OH– conductivity is 10 to 100 times higher than that of conventional OH– conductors, and is the highest even among inorganic anion conductors. LDH nanosheets may be applicable as solid electrolytes for alkaline fuel cells and water electrolyzers, among other devices.