An empirical model is proposed to predict the energy position of the metal-to-metal charge transfer (MMCT) bands in closed shell d(0) transition metal complex oxides doped with Bi3+ or Pb2+ ions. The model is constructed on the basis of optical data compiled from the literature and from the investigation of the luminescence properties of a series of compounds (titanates, vanadates, niobates, tantalates, molybdates, and zirconates) prepared and characterized in this work. (C) 2011 Elsevier B.V. All rights reserved.