Radium hydroxide is an inorganic compound of radium, hydrogen, and oxygen with the chemical formula Ra(OH)2.

[1] Stability constant of aqueous RaOH+ ion pair at zero ionic strength is equal to 5.

[2] Radium hydroxide forms colorless crystals that dissolve in water better than does barium hydroxide, and has more basic properties.

The compound forms a hydrate of the composition Ra(OH)2·8H2O.

[3] Radium hydroxide is a caustic, toxic, and corrosive substance.