To evaluate the effects of H₂S on sulphide stress cracking (SSC) resistance and on localised corrosion of a powder metallurgically (P/M) produced super duplex stainless steel and on wrought duplex stainless steels slow strain rate tests (SSRT) and U-bend tests were performed. Tests showed that SSRT method is an aggressive test, since brittle fracture behaviour was observed even with a small amount of hydrogen sulphide in the solution. Pitting corrosion resistance of duplex stainless steels is improved as the content of alloying elements is so high that the pitting resistance number exceeds the value of about 40. Additionally, SSRT tests were performed in an inert nitrogen environment in the temperature range of 25–250°C. In the testing temperature of 177°C and above small brittle facets were locally observed in the ferrite phase of otherwise ductile fracture surfaces.