Climate change is one of the major issues facing the world today. The energy sector is looking at hydrogen as a solution to minimise carbon emissions, and hydrogen can play an important role. Hydrogen energy in the future will require a transportation and storage system, depending on the demand. There is a lack of data on the behaviour of hydrogen in underground environments with materials to be used in storage and transportation facilities. Oil and gas companies tend to use carbon steel for transportation and storage facilities because of its easy availability, economic cost and the required strength. Hydrogen molecules under pressure tend to decompose to a small extent on the surface of steel and other metallic materials, and the metal can uptake hydrogen as atoms. Depending on the strength of the steel and other conditions, the absorbed atomic hydrogen tends to embrittle steels, which can lead to unforeseeable and catastrophic failures. Therefore, Materials like carbon steels, which are mentioned in the API 5CT, such as K55, L80, N80Q and C90 in an environment with a mixture of H2, CO2, and H2S are used with a brine with 5% NaCl. Amount of absorbed hydrogen in the material analysed with Thermal Desorption Spectroscopy (TDS). Constant load tests and slow strain rate tests, and Fatigue and fracture Mechanics tests are performed. The aim of this research is to study the available steels from the API 5CT standards and find out if they are suitable for using underground hydrogen storage. The first results look promising, that no substantial embrittlement as reduction of a lifetime was not far expected in most steel environment systems.