Strontium hydroxide, Sr(OH)<sub>2</sub>, is a caustic alkali composed of one strontium ion and two hydroxide ions. It is synthesized by combining a strontium salt with a strong base. Sr(OH)<sub>2</sub> exists in anhydrous, monohydrate, or octahydrate form.
Because Sr(OH)<sub>2</sub> is slightly soluble in cold water, its preparation can be easily carried out by the addition of a strong base such as NaOH or KOH, drop by drop to a solution of any soluble strontium salt, most commonly Sr(NO<sub>3</sub>)<sub>2</sub> (strontium nitrate). The Sr(OH)<sub>2</sub> will precipitate out as a fine white powder. From here, the solution is filtered, and the Sr(OH)<sub>2</sub> is washed with cold water and dried.
Strontium hydroxide is used chiefly in the refining of beet sugar and as a stabilizer in plastic. It may be used as a source of strontium ions when the chlorine from strontium chloride is undesirable. Strontium hydroxide absorbs carbon dioxide from the air to form strontium carbonate.
Strontium hydroxide is a severe skin, eye and respiratory irritant. It is harmful if swallowed.