Although hydrogen and the possibilities of its wider application have been attracting attention of a (limited) part of the scientific and professional community for decades, its "appearance on the big stage" happened with the adoption of the European Green Deal, a comprehensive strategy of the European Union from December 2019, adopted with the goal of achieving carbon neutrality in 2050. A more comprehensive approach to the role that hydrogen can have in the energy system European Union aims to achieve in its future development, was reached in July 2020 by the adoption of two complementary strategies: EU Hydrogen Strategy for a Climate Neutral Europe and EU Strategy on Energy System Integration. The paper provides an overview of the European and national strategic and regulatory framework for the future role of hydrogen in the development of the gas transmission infrastructure as well as more concrete steps in defining of that role from the perspective of gas transmission system operators, an association working on the development of the hydrogen pipeline network in the EU and European Network of Transmission System Operators for Gas (ENTSOG). In the final section of the paper, theoretical concepts presented in the first part of the paper were tested through a case study on repurposing the Slobodnica - Dravaszerdahely gas pipeline for hydrogen transport. The economic aspect of such an investment, i.e., the integration of hydrogen into the gas transmission system development planning was presented on a specific example.