The oxygen content determines the transport properties of Ba₂YCu₃O_7+x and EuBa₂Cu₃O_7+x, and in particular their superconducting behavior at high temperatures. The authors studied the changes in the Ba₂YCu₃O_7+x electronic structure which are caused by modifications in the amount of oxygen. The modifications were achieved either by thermal annealing or by exposure to `white' synchrotron radiation which causes oxygen desorption, with similar results. They found that the decrease in oxygen content affects the line-shape of the upper valence band features and the relative intensity of the Cu satellite features. The lineshape changes simplify the identification of oxygen-related features in the upper valence band region. The exposure to `white' synchrotron radiation of Ba₂EuCu₃O_7+x did not produce similarly large spectral changes