The corrosion behavior of gun-barrel steel in 37.8% hydrochloric acid (HCl) at room temperature was investigated as a function of exposure time by several methods, including mass loss measurement, atomic absorption spectrometer (AAS), x-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive x-ray analysis (EDX), x-ray fluorescence (XRF), and x-ray absorption fine structure (XAFS). The corrosion rate showed unsteady-state behavior; however, time had no significant effect on the composition of corrosion product. XRD analyses of this surface corrosion indicated the formation of akaganeite (β-FeOOH). Fluorescence XAFS studies revealed that the iron coordination environment in the steel was similar to that of the body-centered cubic (bcc) iron. Surface sensitive total electron yield (TEY) XAFS showed that the structure of the corrosion product was invariant as a function of exposure time.