Structural stability and electronic properties of a corundum (Al1-xCrx)(2)O-3 structure over the whole Cr composition are investigated by means of the full-potential linearized augmented plane-wave method within the local-spin-density approximation (LSDA)+U. Calculated results predict that ordered and disordered states are energetically less favorable with respect to a phase separation, and that interatomic distances do not change over the whole Cr composition, where the Cr-O distance is always larger than the Al-O distance. An antibonding Cr 3d-O 2p hybridization leads to the phase-separated-type phase stability and the structural property. (C) 2012 Elsevier B.V. All rights reserved.