High-entropy alloys differ completely from the alloy system is present in between 5 and 35 at.%. The crystal structures and physical properties of high those of conventional alloys. The electrochemical impedance spectra (EIS) of the AlxCrFe1.5MnNi0.5 (x=0, 0.3, 0.5) alloys, obtained in 0.1 M HCl solution, clearly revealed that the corrosion resistance values were determined to increase from 21 to 34 Omega cm(2) as the aluminum content increased from 0 to 0.5 mol, and were markedly lower than that of 304 stainless steel (243 Omega cm(2)). At passive potential, the corresponding current declined with the anodizing time accounting, causing passivity by the growth of the multi-component anodized film in H2SO4 solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surface of anodized Al0.3CrFe1.5MnNi0.5 alloy formed aluminum and chromium oxide film which was the main passivating compound on the alloy. This anodic treatment increased the corrosion resistance in the EIS measurements, of the CrFe1.5MnNi0.5 and Al0.3CrFe1.5MnNi0.5 alloys by two orders of magnitude. Accordingly, the anodic treatment of the AlxCrFe1.5MnNi0.5 alloys optimized their surface structures and minimized their susceptibility to pitting corrosion. (C) 2008 Elsevier B.V. All rights reserved.