Nickel oxide hydroxide is the inorganic compound with the chemical formula NiO(OH).

Nickel(III) oxides are often poorly characterized and are assumed to be nonstoichiometric compounds.

For applications in organic chemistry, nickel oxides or peroxides are generated in situ and lack crystallographic characterization.

For example, "nickel peroxide" (CAS# 12035-36-8) is also closely related to or even identical with NiO(OH).

[1] Its layered structure resembles that of the brucite polymorph of nickel(II) hydroxide, but with half as many hydrogens.