Born in Kiev, Ephraim Katzir was brought to Eretz Yisrael in 1925. He served in the pre-state Haganah and then studied at the Hebrew University, where he received both his M.Sc. and Ph.D. degrees.

After studying abroad, he returned to Israel after independence and became head of the Department of Biophysics at the Weizmann Institute of Science in Rehovot. He was Chief Scientist of the Israel Defense Forces, 1966-1968.

Katzir earned an international reputation for his original research in the field of polyamino acids. He also developed a synthetic fiber used for stitching internal wounds in surgery, which is dissolved by the body's enzymes.

Known to stress the moral responsibility scientists have to society, Katzir wrote and lectured widely, eventually being the first Israeli to become a member of the U.S. National Academy of Sciences.

He served as President of Israel, 1973-1978. His older brother, Aharon, also a scientist, was killed by a Japanese terrorist at Lod (Ben-Gurion) airport in 1972.