Langmuir was the third of four sons and was only 17 when his father died; but the latter worked in insurance and the family was financially secure. The young man attended the School of Mines at Columbia (New York) and then studied at Göttingen with Nernst. His work there, on the dissociation of gases by a hot platinum wire, began an interest in surface chemistry which he never lost. In 1901 he joined the General Electric Company research centre at Schenectady, NY, and worked there for 41 years. An early success for him was the improvement of tungsten filament lamps, by filling them with inert gas (argon) at low pressure to reduce evaporation and by using a coiled-coil filament. Further work on hot filaments led to the discovery of atomic hydrogen and the invention of a welding torch using its recombination to H2 to achieve 6000°C.
In 1919–21 he worked on ideas of atomic structure, developing the ideas of Lewis to form the Lewis–Langmuir octet theory of valence, which was simple and useful in explaining a range of chemical phenomena. The words electrovalence and covalence were first used by him. His interest in hot surfaces moved to thermionic emission, where his work advanced both theory and practice. His study of surface films on liquids allowed some deductions on molecular size and shape; and his work on gas films on solids led to the Langmuir adsorption isotherm, the first important theory of the adsorption of gases on solid surfaces.
His ideas on surface adsorption advanced understanding of heterogeneous catalysis. He was awarded the Nobel Prize for chemistry in 1932 largely for this, becoming the first scientist fully employed in industry to receive a Nobel Prize. He went on to work on electric discharges in gases, and made the first full studies of plasmas (a word he coined). He was a keen sailor and flyer, and his studies of atmospheric physics led to trials in weather control (eg rain-making by seeding clouds with solid CO2). He had a wide range of interests, including music, conservation and Scouting, and his distinctions include having Mount Langmuir in Alaska named after him.