The Haber process, also called the Haber–Bosch process, is the main industrial procedure for the production of ammonia. The German chemists Fritz Haber and Carl Bosch developed it in the first decade of the 20th century. The process converts atmospheric nitrogen (N2) to ammonia (NH3) by a reaction with hydrogen (H2) using an iron metal catalyst under high temperatures and pressures. This reaction is slightly exothermic (i.e. it releases energy), meaning that the reaction is favoured at lower temperatures and higher pressures. It decreases entropy, complicating the process. Hydrogen is produced via steam reforming, followed by an iterative closed cycle to react hydrogen with nitrogen to produce ammonia.

Fritz Haber was a German chemist who received the Nobel Prize in Chemistry in 1918 for his invention of the Haber–Bosch process, a method used in industry to synthesize ammonia from nitrogen gas and hydrogen gas. This invention is important for the large-scale synthesis of fertilizers and explosives. It is estimated that a third of annual global food production uses ammonia from the Haber–Bosch process, and that this supports nearly half the world's population. For this work, Haber has been called one of the most important scientists and industrial chemists in human history. Haber also, along with Max Born, proposed the Born–Haber cycle as a method for evaluating the lattice energy of an ionic solid.