Potassium hypomanganate is a chemical compound. It contains potassium and hypomanganate ions. It is a bright blue solid. It is unstable and rare. It can be made several ways: reduction of potassium permanganate with potassium sulfite; reduction of potassium manganate with hydrogen peroxide and potassium hydroxide; and disproportionation when manganese dioxide is dissolved in potassium hydroxide. It disproportionates into potassium manganate and manganese dioxide easily. Only a strong base can stop it from disproportionation.