Duplex stainless steels have a microstructure composed of 50% ferrite and 50% austenite. This microstructure confers them high mechanical properties and corrosion resistance. For this reason, these alloys are widely used in subsea environments for gas and oil transportation systems. However hydrogen induced stress cracking is the cause of catastrophic failures in service. To quantify the hydrogen influence on the mechanical properties of duplex stainless steels, this study aims to compare the stress evolution, during constant load tensile testing, on two types of microstructures: forged and hot isostatic pressed duplex stainless steel, with and without hydrogen pre-charging. If successful a comprehensive understanding of hydrogen impact on mechanical properties of duplex stainless steels will be gained and used to further knowledge of the hydrogen induced stress cracking mechanism.