Electronic properties for a set of CdXO3 (X = C, Si, Ge, Sn, Pb) crystals were investigated using the density functional theory (DFT) formalism considering both the local density and generalized gradient approximations, LDA and GGA, respectively. Hexagonal CdCO3 and triclinic CdSiO3 have indirect main energy band gaps while orthorhombic CdGeO3 and CdSnO3 exhibit direct interband transitions. Orthorhombic CdPbO3 has a very small indirect band gap. The Kohn-Sham minimum electronic band gap oscillates as a function of the X ns level, changing from 2.94 eV (hexagonal CdCO3; LDA) to 0.012 eV (orthorhombic CdPbO3; LDA). (C) 2009 Elsevier B.V. All rights reserved.