The absorption spectra of [Ir(ppy) 3 ] and [Ir(ppy) 2 (CO)Cl)] have been calculated by means of TD-DFT methods based on optimized structures, including spin–orbit coupling. Whereas spin–orbit effects modify the spectrum of the tri-substituted phenylpyridine reference complex they do not change significantly the absorption properties of the carbonyl/halide substituted complexes. The absorption spectra have been assigned on the basis of the spin–orbit states and the emissive properties of the complexes have been interprated from the singlet/triplet mixing and spin–orbit splitting of the lowest S 1 singlet and T 1 triplet states. The theoretical results agree rather well with the experimental data available for this class of complexes, reproduce the zero-field splittings observed for the T 1 states at low-temperature and give a new interpretation of the emissive properties. The presence of low-lying mixed XLCT/MLCT states of weak intensities in [Ir(ppy) 2 (CO)Cl)] limits the spin–orbit effects as compared to [Ir(ppy) 3 ], the spectrum of which is characterized by nearly pure MLCT states in the visible energy domain.