Depending on the experimental conditions (composition microstructure stress temperature pH chloride content H2S partial pressure …) Duplex Stainless Steels (DSS) may suffer from uniform corrosion and/or from local corrosion processes that involve the selective dissolution of the ferritic phase or the austenitic phase. These various corrosion phenomena can generate Sulfide Stress Cracking (SSC) or Stress Corrosion Cracking (SCC). The intent of this paper is first to delimit the domain of susceptibility corresponding to these two different forms of Environmentally Assisted Cracking (EAC). The second objective is to discuss the parameters affecting the transition from SSC to SCC.Specimens of UNS S32304 Lean DSS plate have been tested by means of slow strain rate tensile test in solutions containing 50 g L-1 NaCl 5 g L-1 NaCH3COO and under a pressure of 14.5 psi (1 bar) of H2S. Four pH – 2.8 3.5 4.5 and 6 – and three temperatures – 68 °F (20 °C) 122 °F (50 °C) and 194 °F (90 °C) – have been considered.At pH 2.8 and 68 °F (20 °C) SSC occurs due to the uniform corrosion of the ferritic phase. At 122 °F (50 °C) the S32304 Lean DSS is sensitive to SCC. At this temperature selective dissolution of the austenitic phase can be observed along the cracking paths and dissolution of the ferritic phase occurs at different points of the specimen. At 194 °F (90 °C) an “exfoliation corrosion” phenomenon appears and causes SSC. This kind of corrosion affects selectively the ferritic phase and propagates on the surface but is not generalized. The term “exfoliation corrosion” is usually associated with aluminum alloys but here it is employed because of the similar morphology of the observed corrosion.At pH 3.5 and 68 °F (20 °C) SCC occurs associated to some selective dissolution of the austenitic phase along the cracking path. At 122 °F (50 °C) specimens are sensitive to SCC initiated by pitting corrosion and at 194 °F (90 °C) “exfoliation corrosion” phenomenon of the ferritic phase appears once more and causes SSC. At higher pH SCC initiated by pitting corrosion occurs at 68 °F (20 °C) and 122 °F (50 °C) whereas only “exfoliation” corrosion of the ferritic phase without cracking appears at 194 °F (90 °C).The different forms of EAC can be distinguished according to the cause of the dissolution and to its local character. From that distinction delimitations of SSC / SCC susceptibility domains are deduced. Discussion on the transition between the two phenomena is done in terms of difference of depassivation pH between the austenite and the ferrite and of change in dissolution of H2S in water as a function of temperature. Key-words: UNS S32304 stress corrosion cracking sulfide stress cracking H2S