A number of solar cell concepts based on nanostructured semiconducting materials has been developed in recent years, e.g. dye-sensitized solar cells (DSSC), extremely thin absorber layer (ETA) solar cells and other interpenetrating networks of polymers or semiconductors. However, slow electron transport by diffusion in the nanoporous films often leads to a loss of efficiency as a part of the photogenerated charge carriers recombine before they can reach the back contact. Fully accessible 3D mesoporous architectures with a high conductivity are an approach to overcome these shortcomings. We succeeded in the synthesis of such pore architectures based on highly transparent and highly conductive mesoporous indium tin oxide (ITO) with pore sizes suitable for the deposition of a thin semiconductor layer on the pore. The concept was probed by electrodeposition of thin layers of ZnO on the pore walls and their subsequent dye-sensitization. Transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDXS) shows that all the pore walls can be covered with ZnO in the electrodeposition process. Compared to dye-sensitized ZnO layers of the same thickness on flat ITO, the photocurrent is increased by a factor of up to 50. This matches well with the 40-50 times higher specific surface area of the mesoporous ITO films (typically 45 +/- 3 cm²/cm²), showing the good electron transport properties of the porous ITO network. The concept should be of interest not only for use in DSSC, but also for other types of solar cells based on interpenetrating inorganic networks.