Radium hydroxide
3D model (JSmol)
  • InChI=1S/2H2O.Ra/h2*1H2;/q;;+2/p-2
  • [Ra+2].[O-H].[O-H]
Molar mass 260 g·mol−1
Appearance colorless crystals
Related compounds
Related compounds
Barium hydroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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]


Ra + 2H2O → Ra(HO)2 + H2
RaO + H2O → Ra(HO)2

Physical properties

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.[4]

Radium hydroxide is a caustic, toxic, and corrosive substance. It is significantly more toxic than barium hydroxide (Ba(OH)2) and strontium hydroxide (Sr(OH)2).


  1. ^ Brown, Paul L.; Matyskin, Artem V.; Ekberg, Christian (1 June 2022). "The aqueous chemistry of radium". Radiochimica Acta. 110 (6–9): 505–513. doi:10.1515/ract-2021-1141. ISSN 2193-3405. S2CID 248301187. Retrieved 8 June 2023.
  2. ^ Matyskin, Artem V.; Brown, Paul L.; Ekberg, Christian (2019). "Weak barium and radium hydrolysis using an ion exchange method and its uncertainty assessment". Journal of Chemical Thermodynamics. 128: 362–371. doi:10.1016/j.jct.2018.08.037. S2CID 105458974.((cite journal)): CS1 maint: multiple names: authors list (link)
  3. ^ "Alkaline Earth Hydroxide - an overview | ScienceDirect Topics". ScienceDirect. Retrieved 8 June 2023.
  4. ^ Schweitzer, George K.; Pesterfield, Lester L. (14 January 2010). The Aqueous Chemistry of the Elements. Oxford University Press. p. 448. ISBN 978-0-19-974219-6. Retrieved 8 June 2023.