Abstract To utilize the full potential of hydrogen energy in the UK a number of economic, technical and environmental factors must be considered. An important factor in replacing fossil fuels with hydrogen will be the practicality of storing a sufficient quantity to smooth out fluctuations in demand and provide a strategic reserve. This paper investigates the potential for large-scale underground hydrogen storage in the UK by considering the technical, geological and physical issues of storage, the locations of salt deposits, legal and economic aspects. In addition, reference is made to the equations of state applicable to this type of storage. The results of this investigation show that the UK has a number of potential locations where underground storage would provide a strategic reserve of hydrogen.