Manganese(II) hydroxide

Manganese(II) hydroxide is the inorganic compound with the formula Mn(OH)2. It is a white solid although samples darken quickly upon exposure to air owing to oxidation. It is poorly soluble in water.

Manganese(II) hydroxide precipitates as a solid when an alkali metal hydroxide is added to an aqueous solution of Mn2+ salt:

Manganese(II) hydroxide oxidises readily in air, as indicated by darkening of samples.

The compound adopts the brucite structure, as do several other metal dihydroxides.