1. It reacts with more active metals to form ionic hydrides.
2Na(s) + H2(g) → 2NaH(s)
2. It reacts with oxygen to form steam which when condensed form.
2H2(g) + O2(g) → 2H2O(g)
3. It acts as a reducing agent to reduce some less active metallic oxides to the metal.
CuO(s) + H2(g) → Cu(s) + H2O(L)