Climate change is one of the most crucial economic, technical and political challenges of our time. At the heart of the transition towards a sustainable future sits the decarbonisation of our energy supply which requires a monumental engineering effort. This gradual shift away from natural gas leaves an energy supply gap which will partially be filled by green hydrogen from electrolysis. The repurposing of the thereby freed-up gas transport infrastructure for hydrogen seems obvious. The key underlying issue calling the feasibility of such a repurposing into question stems from hydrogen embrittlement. This effect is known since the 1870s and proves critical under the high-pressure gaseous hydrogen conditions in pipelines. To guarantee safety in usage an extensive body of evidence is necessary. This thesis aims to aid the qualification of X42Q line pipe steel and give a comparison with P235 steel, both manufactured by voestalpine Tubulars GmbH & Co KG. To quantify the susceptibility of these materials to hydrogen embrittlement first the saturation hydrogen uptake from different electrochemical charging conditions and gaseous charging was compared. Experiments were conducted in acidic 0,5 M H2SO4 and neutral 3% NaCl solutions containing recombination poisons of either thiourea or arsenic oxide. The current densities driving the reaction were chosen at 1 and 10 mA/cm2 with charging times of 24h and 48h. For gaseous charging with dry H2 pressures of 100 and 1000 bars were held over a period of 7 days. From these results suitable electrochemical charging conditions for slow strain rate testing at a strain rate of 10-5 s-1 were selected. The resulting embrittlement was investigated further via SEM of the fracture surfaces. The results indicate a direct relationship between charging conditions, saturation hydrogen content and brittleness of the fracture. Comparatively X42Q shows a lower susceptibility towards hydrogen embrittlement than P235. It¿s also worth mentioning that P235 experiences blistering under more aggressive charging conditions.