The photophysics of 9(19),16(17),23(24)-tri-tert-butyl-2-[ethynyl-(4-carboxymethyl)phenyl] phthalocyaninatozinc(II) (ZnPc) in solution and adsorbed on TiO 2 and ZrO 2 nanoparticle films is characterized by stationary and time-resolved spectroscopies in the subpicosecond to nano-second time interval. The comparison between the solution and the solid substrate data allows us to identify different pathways of the energy and electron relaxation. On the solid substrate, the presence of H-aggregates adds a further nonradiative deactivation channel competing with the charge injection into the TiO 2-conducting band, thus providing an explanation of the reduced efficiency of the charge transfer processes. The comparison between the kinetics recorded after excitation of the S 0 −S 2 transition and those recorded after excitation of the S 0 −S 1 transition provides an estimate of the internal conversion between S 2 and S 1 which occurs very efficiently and on an ultrafast (<50 fs) time scale. The ground-state recovery characterized by the decay of the bleaching band in the transient spectra slows down in TiO 2 samples and is taken as evidence of the charge injection in this kind of sample.