In this period of transition, attention to the environment and clean sources of energy are topics that are acquiring increasing interest. With particular reference to the energy industry, hydrogen is becoming the ideal candidate for the replacement of fossil fuels. The distribution of hydrogen is forced to be conducted through the usage of the existing net of pipelines; therefore, using pipes fabricated in different periods (from 1970 up to present). This means, the prediction of the behavior of the pipeline steel under H2 charging (gaseous or cathodic) is not easy and requires a big specific effort to be performed. Therefore, in this work a vintage API 5L grade X52 pipe fabricated in 1970 was characterized both under cathodic and gaseous hydrogen environment; a comparison between mechanical tests with in situ H2 charging was compared with results obtained from KIH test in gaseous hydrogen at 80 bar and a complete picture of the behavior of the material was obtained. Furthermore, the results obtained from slow strain rate tests on notched specimens up to 1500 bar are presented and discussed.