We report time-dependent (TD) and coupled -perturbed (CP) DFT/HF investigations, on the linear and non-linear optical properties of M(II)-complexes of [5-[(4 '-dimethylaminophenyl)-ethynyl]-15-[(4 ''-nitrophenyl)ethynyl]-10,20-diphenylporphyrin], with M = Zn, Cu, Ni. The TD-DFT absorption spectrum is in good agreement with the experimental one, allowing us to identify the transitions mainly responsible of the NLO response. CP-DFT/CP-HF calculations provide similar hyperpolarizability values for the three complexes, suggesting an irrelevant role of the metal center. A sharp hyperpolarizability increase is calculated at an incident laser wavelength of 1.064 mu m compared to 1.907 mu m, which seems to be responsible for the large differences between Zn, Cu and Ni complexes reported experimentally. (c) 2007 Elsevier B.V. All rights reserved.