The importance of passive film stability and mechanical properties of the UNS (1) S32304, S32202 and S32101 Lean Duplex Stainless Steel grades on Stress Corrosion Cracking (SCC) is discussed in this paper. Measurement of uniform corrosion resistance in the presence of H 2 S, through polarization curves, and slip steps height and spacing, through Atomic Force Microscopy technique (AFM) have been performed. Results show that, as opposed to N, Mn decreases the passive film stability and slip steps height and spacing at the surface of the austenitic phase. Therefore, on the basis of slow strain rate tensile tests where the grade S32202 show a greater SCC resistance than the grades S32304 and S32101, it can be concluded that the electrochemical passive film stability makes the larger contribution to SCC phenomenon and so the negative impact of Mn.