It is also easily formed as a by-product of other reactions, a.o., in the synthesis of siderite, an iron carbonate (FeCO3), if the crystal growth conditions are imperfectly controlled.

This process is described by the Schikorr reaction: Anions such as selenite and selenate can be easily adsorbed on the positively charged surface of iron(II) hydroxide, where they are subsequently reduced by Fe2+.

[7] The natural analogue of iron(II) hydroxide compound is the very rare mineral amakinite, (Fe,Mg)(OH)2.

[8][9] Iron(II) hydroxide has also been investigated as an agent for the removal of toxic selenate and selenite ions from water systems such as wetlands.

[10] In a basic solution iron(II) hydroxide is the electrochemically active material of the negative electrode of the nickel-iron battery.