The electron transport in dye-sensitized solar cells with a MOCVD (metal organic vapor deposition)-grown ZnO nanorod array (ZnO-N) or a mesoporous film prepared from ZnO colloids (ZnO-C) as the working electrode was compared. The electrodes were of similar thickness (2 mum) and sensitized with zinc(II) meso-tetrakis(3-carboxyphenyl)porphyrin, while the electrolyte was I(-)/I(3)(-) in 3-methoxypropionitrile. Electron transport in the ZnO-C cells was comparable with that found for colloidal TiO(2) films (transport time approximately 10 ms) and was light intensity dependent. Electron transport in solar cells with ZnO-N electrodes was about 2 orders of magnitude faster ( approximately 30 mus). Thus, the morphology of the working ZnO electrode plays a key role for the electron transport properties.