The study analyzes the techno-economic feasibility and business case of large-scale hydrogen underground storage in France. Potential regions for locating the storage cavity were assessed, as well as the anticipated hydrogen demand and renewable energy developments. The business case of salt caverns storage facility has been assessed both in 2025 and 2050, looking at several demand sectors, including mobility (FCEVs), hydrogen consuming industries and what is defined as "Power-to-Gas". The hourly operation of the cavern has been modeled. The electricity supply is restricted to wind and grid electricity only. The mobility market is clearly the key driver, both in quantity and economic terms, with an easier to achieve target cost ((sic)4/kgH2, ex-storage). High utilization rates of electrolysers are necessary to reach profitability. A need for massive storage begins for a renewable penetration rate of 50%. The hydrogen costs varies from (sic)4.5/kg to (sic)6.6/kg H2, and the underground mass storage cost remains always under 5% of the overall costs. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.