Barium hydroxide is the chemical compound with the formula Ba(OH)₂. Also known as baryta, it is one of the principal compounds of barium. The white granular monohydrate is the usual commercial form.

Calcium hydroxide, traditionally called slaked lime, hydrated lime, slack lime, or pickling lime, is a chemical compound with the chemical formula Ca(OH)₂. It is a colourless crystal or white powder, and is obtained when calcium oxide (called lime or quicklime) is mixed, or "slaked" with water.

Lithium hydroxide (LiOH) is a corrosive alkali hydroxide. It is a white hygroscopic crystalline material. It is soluble in water, and slightly soluble in ethanol. It is available commercially in anhydrous form, or as the monohydrate.

Magnesium hydroxide is an inorganic compound with the chemical formula Mg(OH)₂. As a suspension in water, it is often called milk of magnesia because of its milk-like appearance. The solid mineral form of magnesium hydroxide is known as brucite.