This work reports a theoretical study of the x-ray absorption near-edge structure spectra at the Cu K edge in several Cu(II) complexes with N -coordinating ligands showing a square-planar arrangement around metal cation. It is shown that single-channel multiple-scattering calculations are not able to reproduce the experimental spectra. The comparison between experimental data and ab initio computations indicates the need of including the contribution of two electronic configurations (3 d9 and 3 d10 L) to account for a proper description of the final state during the photoabsorption process. The best agreement between theory and experiment is obtained by considering a relative weight of 68% and 32% for the two absorption channels 3 d10 L and 3 d9, respectively Comisión Interministerial de Ciencia y Tecnología MAT2002-04178-C04-03, BQU2002-02217 y BQU2002- 04364-C02-01