Kohn, Walter (1923-) is an Austrian-born American physicist most noted for his investigations into the electronic structure of solid-state matter. His contributions have led to major advancements in the areas of superconductivity, semiconductors, and surface physics. Kohn shared the 1998 Nobel Prize in chemistry with the British chemist John Anthony Pople for their studies of the properties of molecules and the chemical processes involving molecules.

During World War II (1939–1945), Kohn and his sister immigrated to Britain to escape the Nazis. He was interned there and in 1940 sent to Canada, where he completed his B.A. and M.A. degrees at the University of Toronto. After receiving his Ph.D. degree in physics from Harvard University, Kohn taught there and then at the Carnegie Mellon Institute of Technology. He then served as professor of physics and as department head at various branches of the University of California, most recently at the University of California, Santa Barbara. In 1979, the National Science Foundation established the National Institute of Theoretical Physics at Santa Barbara, appointing Kohn its founding director. Under his direction, the institute has attracted leading physicists and now serves as the outstanding model for other facilities of its kind.

Kohn has spent his long career studying the characteristic structure and interactions of electrons in solid-state matter, especially the electronic structure of metals, and his achievements include significant advances in surface physics, the physics of semiconductors, and superconductivity. Kohn was awarded the 1998 Nobel Prize in chemistry for developing the density functional theory (DFT), which is used for electronic materials science. DFT is a mathematical method with simplified calculations that enable scientists in numerous disciplines to approach the study of the electronic structure of atoms, molecules, and solid matter in practical new ways. It describes the ground state properties of such things as semiconductors, insulators, and metals. Kohn retired from the University of California, Santa Barbara, in 1991 and now holds the title of emeritus professor there.