The noble interest of this article is the study, the effect of heat treatments at low temperatures at -196°C and structure on the mechanical behaviour of steels cathodically charged with hydrogen. The standardized tensile test specimens undergo characterization techniques by mechanical test, hardness, tensile. Underwent austenization heat treatments for 35minutes at 1050°C following a rapid water quench, following by a tempering for 30 minutes at 680°C, after having a cryogenic quenching for 30minutes by the liquid nitrogen (N₂) gaz at -196°C in immersion succession ranging from 20cycles time. A cathodic loading was in a pyrex cell to be filled with an aqueous solution of sulfuric acid H₂SO₄ at 0.05M for different loading times from 1hour to 8hours with a step of 1hour. The application of these methods and technicals aims to improve the mechanical properties of these respect to the embrittlement mechanism. The results of the different mechanical properties given in the form of experimental curves to be noted after the mechanical fracture test by tensile at ±20°C temperature using an instrumented tensile machining reference : Frank GMBH, with industrial conditions, the maximum load is constant at 400KN and nominal speed deplacement at (έ=23.0mm/min).