First principle quantum chemical methods have been employed in the calculations of the linear and nonlinear ground state absorption in platinum-organic compounds, some of which include charge-transfer groups. The theoretical results show several ways to tailor the linear absorption to a desired wave length region. Spin-orbit induced transitions are discussed and characterized. The nonlinear absorption cross-sections are strongly enhanced by the introduction of charge-transfer units, whereas the linear oscillator strengths remain essentially unaffected by the same ligand substitutions. The charge-transfer substitutions are also accompanied by red-shifts in the linear absorption spectra. © 2002 Elsevier Science B.V. All rights reserved.