My guess is that they are different.

I think hydrated oxides would have a lattice with the cation and oxide anions as lattice points and molecules of water trapped in interstitial spaces, while hydroxides would have the cation and hydroxide anions as lattice points with no water molecules in interstitial spaces.

  • $\begingroup$ I think that when we talk about bases, we immediatly have to do with hydroxides because they contain the hydroxide group OH-. Hydrated oxides on the other hand can be only simple oxides who contain also Hydrogen. I didn't find anything on the internet so this is just a thought. $\endgroup$ May 6, 2015 at 20:39
  • $\begingroup$ $\ce{Mn(OH)2}$ is a hydroxide while $\ce{MnO(OH)2}$ is a hydrated oxide. $\endgroup$ Jun 20, 2016 at 10:55
  • 4
    $\begingroup$ Maybe hydrated oxides don't even have a lattice; that's not important. What is important is their non-stoichiometric composition. $\endgroup$ Mar 15, 2017 at 5:34
  • $\begingroup$ This formular $\ce{[Zr4(OH)8 *16 H2O] ^{8+} }$ is a "white gel called zirconium hydroxide but generally considered to be a hydrous oxide" from Nielsen 2005 $\endgroup$
    – zs11
    May 13 at 13:17

1 Answer 1


Hydrated oxide is a compound of an oxide with water. And Hydroxide is a diatomic anion with chemical formula OH− ( a hydroxyl functional group). you can refer to this link for better understanding : http://www.memidex.com/hydrated-oxides. Also looking at the definition of hydration might be helpful. Hydration def picture


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