Propylene oxide is a colorless liquid with an ethereal odor. It is highly flammable and soluble in water and alcohol. Propylene oxide is a precursor of polyols, which in turn can be used to produce polyurethane. Together with thyssenkrupp Industrial Solutions, Evonik Active Oxygens has co-developed the HPPO process, which can produce propylene oxide from propene and hydrogen peroxide in an environmentally compatible way.