The electronic structure of CaO and SrO in the ground state is calculated in terms of the crystalline cluster approach. Calculations for 27‐atom clusters at different ratios between muffin‐tin sphere radii show that in both crystals the charge configuration is similar to that obtained earlier for MgO: Mg2+ ‐O− plus one electron, distributed in the interstitial region. Such distribution of the electronic density is interpreted in terms of the theory of resonance scattering on the anion effective potential.