A limiting factor at high light intensities in dye-sensitized mesoscopic thin film solar cells seem to be the transport of charge through the electrolyte. To get valid parameters to feed into an over all model for a solar cell based on mesoscopic thin films, we are currently studying the obstructed diffusion of reversible redox film thickness, porosity and temp. We will present data from these studies on solvents and redox systems of relevance for mesoscopic electrodes. We believe that the information gained will be of importance for the modeling and optimization of not only the dye-sensitized solar cells, but also for the optimization of the performance of other devices, such as displays and batteries, based on nanostructured semiconducting electrode films.