Titanium is widely used in demanding applications, such as in aerospace. Its strength-to-weight ratio and
corrosion resistance make it well suited to highly stressed rotating components. Zirconium has a no less
critical application where its low neutron capture cross section and good corrosion resistance in hot water and
steam make it well suited to reactor core use, including fuel cladding and structures. The similar metallurgical
behaviour of these alloy systems make it alluring to compare and contrast their behaviour. This is rarely
undertaken, mostly because the industrial and academic communities studying these alloys have little
overlap. The similarities with respect to hydrogen are remarkable, albeit potentially unsurprising, and so this
paper aims to provide an overview of the role hydrogen has to play through the material life cycle. This
includes the relationship between alloy design and manufacturing process windows, the role of hydrogen in
degradation and failure mechanisms and some of the underpinning metallurgy. The potential role of
some advanced experimental and modelling techniques will also be explored to give a tentative view of
potential for advances in this field in the next decade or so.