Polymer materials are used in numerous applications where the knowledge and the control of their transport properties are required. An interesting example is the case of plastic pipes used for gas distribution network. In the context of new energy, hydrogen is taking a growing place and its introduction in existing distribution pipes as a mixture with natural gas can be an alternative to its transport. Due to safety and economic reasons, one of the main questions concerns the possible leakage of hydrogen by permeation through the pipe. The objective of this paper is to evaluate the introduction of hydrogen in the existing natural gas infrastructures in term of barrier properties of mixtures of hydrogen and natural gas. Permeation measurements were performed by IFP on unaged PE100 material samples in various conditions of pressure, hydrogen content and temperature. The specific permeability equipments used for gas mixtures will be described as well as the methods used to calculate the intrinsic transport coefficient and to detect potential particular affinities of a polymer for a gas. Recently, a specific device for the evaluation of hydrogen permeability of pipes has been also developed to test pipes under hydrogen in service conditions. It is then possible to compare data obtained on disc samples and pipes faced to different pressures and different mixtures of natural gas and hydrogen in order to evaluate the processing influence. This is very important to have such a powerful tool in the characterization of innovative systems with enhanced barrier characteristics.