Hydrogen is the lightest gas of all. The most important techniques of producing hydrogen are catalytic reforming (steam reforming) and chlorine-alkali electrolysis. Due to its physical and chemical properties, hydrogen can be used for a large number of industrial purposes: As a fuel gas for special applications, and as a protective gas for heat treatment, foodstuffs technology and electronics. Hydrogen's high thermal conductivity also makes it suitable for use as a coolant for power generators, for instance.

More than two-thirds of the hydrogen produced worldwide is used by the chemical industry. Most of this quantity is employed for the synthesis of ammonia and methanol. The chemical industry also makes use of numerous hydrogenation techniques, sometimes referred to as hydrofining or hydrotreating. Of late, hydrogen has also been discussed as a future source of alternative energy.