The adsorption behavior of dodecanoic acid and its sodium salt (DDAS) as an anionic inhibitor on the galvanic electrode has been investigated by using electrochemical methods, Fourier transform infrared spectroscopy (FT-IR), and atomic force microscopy (AFM). The galvanic electrode was prepared by coupling N80 carbon steel (CS) and S31803 stainless steel (SS), and all experiments were performed in NaCl solution at pH 4 in the presence or absence of DDAS. Electrochemical experiments reveal SS and CS carry positive and negative excess charges in NaCl solution at pH 4, and DDAS is mainly anodic type inhibitor for the galvanic corrosion. FT-IR and AFM were used to analyze the protective layer formed on the electrodes, a stronger adsorbability of the inhibitor on the anode (CS) of GE was measured. Results indicate the protective layer formed on the single CS electrode is less compact than which on the coupled CS. The adsorption regulation of anionic inhibitor on the galvanic electrode is summarized based on the results obtained from electrochemical methods, FT-IR and AFM. (c) 2006 Elsevier B.V. All rights reserved.