Organic films derived from o-methoxyaniline water solution were deposited on GaAs electrodes in an adsorption process. The photoelectrochemical behavior of the modified electrodes was examined by potentiodynamic and potentiostatic methods. The film morphology dependencies on the monomer concentration in the bulk of solution, electrode potential and oxidation time were monitored by in situ atomic force microscopy The monitored morphology changes were correlated with the changes in the photocurrent. The differences in the onset potentials and photocurrent magnitude were explained in terms of the formation of a continuous organic film and on the basis of the p-n junction creation at the GaAs/organic film interface. It is suggested that the organic film mediates transfer of the photocharge to the solution. Based on morphological changes in the deposited film and the spectrophotometric data, the formation of the leucoemeraldine, a reduced form of poly (o-methoxyaniline) is proposed.