In this paper, aryl films are grafted via electrochemical reduction of two different diazonium salts, 4-nitrobenzenediazonium tetrafluoroborate and Fast Red AL salt, in different conditions on polycrystalline copper electrodes. For the surface modification, "normal" electrografting, redox grafting (AG) and for the first time, RG and rotating disk electrode combined method are used. The obtained aryl films are characterized by X-ray photoelectron spectroscopy and atomic force microscopy. Surface concentrations of redox active moieties are determined in acetonitrile and highest values of ca. 25 and 12 nmol cm(-2) are obtained in case of nitrophenyl and anthraquinone films, respectively. Different aryl films exhibit unequal blocking action toward ferricyanide probe and also variable degree of inhibition of the O-2 reduction rate.