The structural and electronic properties of La 2−x Ba x CuO 4 were investigated as a function of Ba-concentration 0 ≤ x ≤ 1.2, within the virtual crystal approximation (VCA) by means of firstprinciples total-energy calculations. We found Ba doping induces a quasi-rigid displacement of Cu d x 2 −y 2 and d z 2 bands toward higher energies. This effect generates important changes in the Fermi surface topology, which manage to imitate the ARPES momentum distribution map (MDM) measurements and tight-binding calculations recently reported for doped La-based cuprates. The calculations exhibit the significant increase in the contribution of Cu d z 2 states at the Fermi level for greater Ba doping content to 0.3, which has effects on orbital hybridisation with Cu d x 2 −y 2 states and therefore in the suppression of the superconducting state. For this Ba doping range, no magnetism was found.