Cathodic electrodeposition in an aqueous solution containing zinc nitrate and riboflavin 5'-phosphate (R5-P) resulted in a formation of porous ZnO thin film modified with R5-P. Surface morphology of the deposited films changed depending upon the dye concentration in the deposition bath, suggesting its strong chemical interaction with the growing surface of ZnO. Optical analysis has confirmed the presence of R5-P species in the film, The as-deposited ZnO/R5-P thin film electrode exhibited anodic photocurrent upon visible light irradiation, indicating the sensitization of ZnO by incorporated R5-P molecules.