A time constant of 13 fs was measured via transient absorption for electron transfer from the excited singlet state of the chromophore perylene into anatase TiO 2 , when the chromophore was bonded to the surface via a carboxyl group. This result suggests that a similarly short time constant should be valid also for primary charge separation from the bipyridyl ligand of the so-called N3 ruthenium dye into anatase TiO 2 . The electron transfer time of perylene became much longer, 3.8 ps, at a distance of about 1.3 nm. Laser pulse induced transients of the photocurrent were measured in the Grรคtzel-cell (G-cell) for illumination firstly through the SnO 2 /TiO 2 interface (SE) and secondly through the opposite SnO 2 /electrolyte interface (EE). For EE illumination the transient showed two peaks, the first in the s range and the second in the ms range. For SE illumination only the early peak was observed. The different shapes of EE compared to SE transients were easily modeled employing a time dependent diffusion equation and appropriate boundary conditions. The experimental rise to the early peak occurred faster than corresponds to diffusion controlled final charge separation at the SnO 2 /TiO 2 interface if the same diffusion constant was assumed that was valid in the bulk of the nm-structured sponge-type TiO 2 /electrolyte layer. The significance of this experimental result for photovoltaic energy conversion of the G-cell is discussed.