Swiss chemist who, with Philip S. Hench (Hench, Philip Showalter) and Edward C. Kendall (Kendall, Edward Calvin), received the Nobel Prize for Physiology or Medicine in 1950 for his discoveries concerning hormones of the adrenal cortex.

Reichstein was educated in Zürich and held posts in the department of organic chemistry at the Federal Institute of Technology, Zürich, from 1930. From 1946 to 1967 he was professor of organic chemistry at the University of Basel. He received the Nobel Prize for research carried out independently on the steroid hormones (steroid hormone) produced by the adrenal cortex, the outer layer of the adrenal gland. Reichstein and his colleagues isolated about 29 hormones and determined their structure and chemical composition. One of the hormones they isolated, cortisone, was later discovered to be an anti-inflammatory agent useful in the treatment of arthritis. Reichstein was also involved in developing methods to synthesize the hormones he had discovered, among them cortisone and desoxycorticosterone, which was used for many years to treat Addison's disease.

Apart from hormone research, Reichstein is also known for his synthesis of vitamin C, a feat achieved about the same time (1933) in England by Sir Walter N. Haworth and coworkers. In the latter part of his career, Reichstein studied plant glycosides, chemicals that can be used in the development of therapeutic drugs. He was awarded the Copley Medal of the British Royal Society in 1968.