Self-consistent scalar-relativistic band structure calculations have been performed to investigate the electronic structure and ground-state properties of alkali-metal oxides Li2O, Na2O, K2O and Rb2O in cubic antifluorite (anti-CaF2-type) structure using the linear muffin-tin orbital in its tight-binding representation (TB-LMTO) method. The calculated ground-state properties of these compounds such as equilibrium lattice parameter and bulk modulus are in agreement with the other theoretical calculations and experimental results. The results of the electronic structure calculations show that Li2O, K2O and Rb2O are indirect band gap semiconductors, whereas Na2O is found to be a direct band gap semiconductor. © 2007 Elsevier B.V. All rights reserved.