The passivity of AISI 316L stainless steel (AISI 316L) in 0.05 M H2SO4, in the steady-state condition, has been explored using various electrochemical techniques, including potentiostatic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis. Based on the Mott-Schottky analysis in conjunction with the point defect model (PDM), it was shown that the calculated donor density decreases exponentially with increasing passive film formation potential. The thickness of the barrier layer was increased linearly with the film formation potential. These observations were consistent with the predictions of the PDM, noting that the point defects within the barrier layer of the passive film are metal interstitials, oxygen vacancies, or both. Also no evidence for p-type behavior was obtained, indicating that cation vacancies do not have any significant population density in the passive film.