A scanning electrochemical microscope (SECM) in the feedback and generation collection modes was used to investigate the regeneration of photoexcited dye cations at the semiconductor/electrolyte Inter face in a dye-sensitized solar cell (DSSC) based on ZnO/D149 An effective dye regeneration rate constant k(ox) of 9 55 x 10(7) CM9/2 Mol(-3/2) s(-1) was obtained from feedback mode experiments at different wavelengths and light intensities on ZnO/D149 electrodes Illuminated regions of the dye-sensitized electrodes could be differentiated from non-illuminated regions by local imaging in SECM generation-collection experiments with I as redox mediator We also report SECM feedback measurements on non-illuminated dye-sensitized electrodes to investigate the electron transfer kinetics of dissolved redox couples at the underlying FTO substrate (C) 2010 Elsevier B V All rights reserved