Hydrogen is a very important molecule with an enormous breadth and extent of application and use. It is currently being used in many industries, from chemical and refining to metallurgical, glass and electronics. Hydrogen is primarily used as a reactant. But it is also being used as a fuel in space applications, as an “O2scavenger” in heat treating of metals and for its low viscosity and density. In this paper, current industrial uses of hydrogen in various industries in the industrial world will be summarized. Due to the increased use of heavier crude oils, containing higher amounts of sulfur and nitrogen and to meet stringent emission standards, need for hydrogen is experiencing a very rapid growth in the petroleum refining industry. Hence this application will be discussed in more detail.