Abstract: Copper(II) hydroxide is produced by a reaction of copper oxychloride in an aqueous suspension with alkali hydroxide or alkaline earth metal hydroxide in the presence of a stabilizing agent and the product is separated and washed. To improve the stability of the copper hydroxide and to avoid a black coloring by copper oxide, inorganic silicon compounds which contain hydroxyl groups (SiOH) in the molecules or form such groups in an aqueous medium are added to the suspension. It is desirable to use particulate solid silicic acids or silicic acids which are soluble in water or colloidally dissolved.

Abstract: In a process of producing cupric hydroxides, products having a high stability in storage will be obtained if phosphate ions are added to a suspension of copper oxychloride in an aqueous phase, the copper oxychloride is then reacted with alkali metal hydroxide or alkaline earth metal hydroxide, and the cupric hydroxide precipitated as a result of the suspension is washed and then re-suspended and subsequently stabilized by the addition of acid phosphate to adjust a pH value of 7.5 to 9. The suspended copper oxychloride is preferably reacted in the presence of phosphate ions in an amount of 1 to 4 grams per liter of the suspension and at a temperature of 20.degree. to 25.degree. C. and the resulting cupric hydroxide is stabilized with phosphate ions in an amount of 3 to 6 grams per liter of the suspension.