A comparative study of the photoelectrochemical properties of nanocrystalline microporous, compact polycrystalline and single-crystal TiO2 electrodes has been performed with an emphasis on the analysis of the short-wavelength region of the action spectra. Adding to the solution or immobilizing on the electrode surface some electron or hole scavengers has been shown to exert significantly more appreciable influence on the short-wavelength edge of photocurrent spectra of nanostructured electrodes as compared with those of polycrystalline compact or single-crystal electrodes. This influence is markedly stronger in basic solutions in comparison with acidic ones. The effects observed are explained by the change of limiting steps of the overall photoelectrochemical process in going from the conventional macroscopic to nanostructured electrodes.