The electrochemical corrosion resistance of the passivated Fe-40at.%Al binary alloy has been investigated in sulfuric acid at 25°C. Structural investigations were conducted by XRD method and confirmed a single phase material of the ordered B2 structure. Electrochemical corrosion behavior was determined using potentiodynamic polarization and EIS methods. Anodic polarization measurements revealed a passive behavior of the tested electrode. Detailed characteristics of the Fe-40at.%Al electrode | passive film | solution interface as a function of the electrode potential in the fully passive range of 0.5 E 1.5 V, was investigated. The impedance behavior was determined by a highly doped n-i-n structure (n-type semiconductor – insulator – n-type semiconductor).