Lateral self-exchange of charge across dye-sensitized film is a phenomenon that may play animportant role in effectivizing H2 production from water via solar energy, and shows potential forother interesting applications. The rate of charge movement via lateral self-exchange across afilm is often quantified in terms of apparent diffusivity of charge, Dapp. In this project, it wasinvestigated how Dapp varies with applied potential, as preliminary results had shown resultsinconsistent with current theoretical understanding. To examine this discrepancy, Dapp wascalculated for different applied overpotentials on a ZrO2 film sensitized with the dye D35. It wasconcluded that values of Dapp vary with overpotential close to the dye’s redox potential, aspredicted by theory. Different dyes may yield other results, and further research on the subject isneeded. Interesting and unexplained differences in kinetics for oxidation and re-reduction of thedye were found, which prompts further studies on the matter.