Boron monoxide (B2O) is a chemical compound of boron and oxygen. Two experimental studies have proposed existence of diamond-like[1] and graphite-like[2] B2O, as for boron nitride and carbon solids. However, a later, systematic, experimental study of boron oxide phase diagram suggests that B2O is unstable.[3] The instability of the graphite-like B2O phase was also predicted theoretically.[4]