The structure of the boron suboxide B6O has been refined by the Rietveld method applied on X‐ray powder diffraction data. The samples were prepared by hot pressing amorphous boron and B2O3 and the data was collected with a STOE‐diffractometer equipped with a position sensitive detector. The structure belongs to the α‐boron family and is closely related to the B13C2‐structure. The space group is R3m. There are two oxygen atoms in each large hole formed by the icosahedral B12 framework, along the trigonal axis. The interatomic distance between the oxygen atoms is long, 3.06(2) A. The oxygen atoms are located close to the centre of the boron triangles that are formed by B(1) atoms from three B12 icosahedra. The bonding distance between these boron atoms and the oxygen atom is 1.503(7) A.