Polarization and impedance measurements were carried out on an iron electrode in an anhydrous acetonitrile solution of 0.1 M LiClO4 and 0.01 M FeCl3 containing organic corrosion inhibitors. Thr inhibitors investigated were N,N-dimethylalkylamines CnH2n+IN(CH3)(2) (C(n)DMA, n = 8, 12, 16, and 18) and octanethiol C8H7SH (C8T). These compounds suppressed both cathodic and anodic processes of iron corrosion in the acetonitrile solution. The double-layer capacitances obtained from impedance data for the electrode inhibited with C(n)DMA were markedly lower in the potential region of the cathodic polarization curve than those for the uninhibited electrode. Ultraviolet and visible spectra of the FeCl3 acetonitrile solution containing C(n)DMA revealed the formation of a Fe3+ complex cation with C(n)DMA, and joint adsorption of the complex cation with Cl- on the iron surface was substantiated by X-ray photoelectron spectroscopy of the surface treated with the solution. A surface thiolate of C8T was formed by iia chemisorption on the iron surface, resulting in a decrease in the double-layer capacitance and the cathodic and anodic current densities, respectively.