Thin film electrodes consisting of a TiO₂ powder nanodispersed on different substrates, displaying unusual photoelectrochemical properties have been investigated using EIS method. It was established, that for non-illuminated electrodes, the EIS spectra are characteristic of the substrate; the poorly doped nanodispersed powder is virtually not observed being shunted by parallelly connected substrate capacitance. In contrast, classical sol/gel anatase electrodes yield linear Mott-Shottky plots characteristic of their active layer.