Self-assembled growth of ZnO films modified with N,N'-bis(ethylenesulfate)-3,4,9,10-perylene tetracarboxylic acid diimide (SO3EtPTCDI) has been realized by a one-step cathodic electrodeposition. Scanning electron microscopy and X-ray diffraction examination of the ZnO/SO3EtPTCDI hybrid films has revealed morphological and structural changes with increasing dye concentration in the deposition bath. The photoelectrochemical action spectra demonstrate a significant enhancement of the anodic photocurrent for ZnO/SO3EtPTCDI electrodes in comparison to that of pure ZnO electrodes, thus evidencing photosensitization of ZnO by the adsorbed dye molecules. A maximum incident photon-to-current conversion efficiency of 7.0% was obtained for such hybrid thin-film electrodes. Impedance measurements indicated a positive shift of the flatband potential of ZnO as a consequence of dye adsorption, enabling the injection of photogenerated electrons from the lowest unoccupied pi-molecular orbital of SO3EtPTCDI into the conduction band of ZnO. (C) 2003 The Electrochemical Society.