KCN is formed by the treatment of hydrogen cyanide with aqueous potassium hydroxide solution, accompanied by the vacuum evaporation in the solution: HCN + KOH KCN + H2O. It produces about fifty,000 tons of potassium cyanide each year.Potassium cyanide is an inorganic compound with the chemical formula KCN, also called potassium cyanide or potassium