OH bonds are present in a wide variety of minerals in the form of structural units or as point defects. In this special issue we invite authors to submit papers providing overviews of recent research on OH in minerals. The reviews may address any specific aspects of OH in minerals: crystallography, speciation, impact on mineral properties, quantitative analyses, natural occurrence, geological implications, or any other relevant topics. This special issue is open to any kind of minerals, hydrous or anhydrous. Papers can focus on any specific envelope of the Earth from soil to the deepest part of the planet.