EN
Al K_{α} excited photoelectron spectra (X-ray photoelectron spectroscopy) of the O 1s, Cu 2p, Ca 2p, Sr 3d core levels were measured for "infinite chain" Ca_{2}CuO_{3} and Ca_{0.5}Sr_{0.5}CuO_{2} compounds. The analysis indicates that for Ca_{2}CuO_{3} the surface electronic structure is strongly influenced by a humid atmosphere. The surface layer is formed predominantly by copper hydroxide. The minor features of Cu 2p and O 1s are characteristic of the bulk bonding states. The valences of the Cu, Ca, and Sr atoms are close to 2+. The core electron binding energies (≈ 934 eV peak) are due to the 2p_{3/2}3d^{10}L^{1} configuration of Cu(II) ions in the square planar coordination for both samples.