New polyamides containing disulfide bonds in their main chains are prepared by condensation between 3,3’-dithiodipropionic acid and various alkyldiamines (NH2-(CH2)(n)-NH2, n = 4 and 12, polyamide I and II). The polyamides form a thin layer on a gold substrate. The surface of polyamide modified electrodes were investigated by AFM and XPS measurements. The surface structure depends on the polyamide structure, especially alkyl chain length of the polyamide. Furthermore, adsorption of ferrocene derivatives [1-ferracenylmethanol (FME) or 2-amino-3-ferrocenylpropionic acid (AFP)] on the polyamide modified electrodes and their electrochemical responses were investigated. Interaction between the polyamide on the electrode and the ferrocene derivatives depends on the structure of the ferrocene derivatives and polyamide chain length. (C) I997 Academic Press