If both the technological and commercial potential of nanostructured metal oxide electrodes are to be fully realized, it will be important to understand the effects of electrolyte composition on the extent of electron accumulation and the nature of charge compensation at different applied potentials. Having studied the potential dependent optical absorption spectroscopy of nanostructured TiO2 (anatase) electrodes in different electrolytes we concluded that the extent and nature of charge accumulation and compensation depends on whether the potential applied corresponds to weak (< 40 mC cm(-2)) or strong (> 40 mC cm(-2)) accumulation conditions, on whether the electrolyte is prepared using a protic or aprotic solvent, and on whether the ions present in the electrolyte are capable of being intercalated or not.