Cobalt(III) hydroxide

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Cobalt(III) hydroxide
IUPAC name
Cobalt(III) hydroxide
Other names
Cobaltic hydroxide
3D model (JSmol)
ECHA InfoCard 100.013.776 Edit this at Wikidata
EC Number
  • 215-153-0
  • InChI=1S/Co.3H2O/h;3*1H2/q+3;;;/p-3 checkY[pubchem]
  • [OH-].[OH-].[OH-].[Co+3]
Molar mass 109.95522 g
Appearance brown-black or dark green powder
GHS labelling:
GHS07: Exclamation markGHS08: Health hazard
H319, H334, H413
P261, P264, P273, P280, P285, P304+P341, P305+P351+P338, P337+P313, P342+P311, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Cobalt(III) hydroxide or cobaltic hydroxide is a chemical compound with formula Co(OH)
or H
. It is an ionic compound, with trivalent cobalt cations Co3+
and hydroxyl anions OH

The compound is known in two structurally different forms, "brownish-black" and "green". The brownish-black form is a stable solid and can be prepared by reaction of water solutions of cobalt(II) chloride and sodium hydroxide, followed by oxidation with ozone.[1]

The green form, formerly thought to be cobalt(II) peroxide, apparently requires carbon dioxide as a catalyst. It can be prepared by adding hydrogen peroxide to a solution of cobalt(II) chloride in 96% ethanol at –30 to –35°C, then adding a 15% solution of sodium carbonate in water with intense stirring. The resulting dark green powder is fairly stable at liquid nitrogen temperature, but at room temperature it turns dark brown within a few days.[2]

Natural occurrence[edit]

Cobalt(III) hydroxide is unknown among the known mineral species (as of 2020). However, heterogenite, CoO(OH), is known.[3][4]

See also[edit]


  1. ^ Pankratov, D.A., Veligzhanin, A.A., and Zubavichus, Y.V. (2013): "Structural Features of Green Cobalt(III) Hydroxide". Russian Journal of Inorganic Chemistry, volume 58, issue 1, pages 67–73. doi:10.1134/S0036023613010142
  2. ^ Pankratov, D.A., Portachenko, T.A., and Perfil’ev, Y.D. (2008): "Emission Mössbauer Study of 'Cobalt Peroxide'". Moscow University Chemical Bulletin, volume 63, issue 5, pages 292–296. doi:10.3103/S002713140805012X
  3. ^ "Heterogenite".
  4. ^ "List of Minerals". 21 March 2011.