Efraim Katchalski was the son of Yehuda and Tzila Katchalski, in Kiev, in the Russian Empire. In 1925, he immigrated to Mandatory Palestine with his family to escape Soviet terror by the newly-elected Joseph Stalin and settled in Jerusalem. In 1932, he graduated from Gymnasia Rehavia.A fellow classmate, Shulamit Laskov, remembers him as the "shining star" of the grade level. He was “an especially tall young man, a little pudgy, whose goodness of heart was splashed across his smiling face.” He excelled in all areas, “even in drawing and in gymnastics, where he was no slouch. He was the first in the class in arithmetic, and later on in mathematics. No one came close to him.” Like his brother, Aharon, Katzir was interested in science. He studied botany, zoology, chemistry and bacteriology at the Hebrew University of Jerusalem. In 1938, he received an MSc, and in 1941, he received a PhD degree from New York University. In 1939, he graduated from the first Haganah officers course, and became commander of the student unit in the field forces. He and his brother worked on development of new explosives. In May 1948, Ephraim was appointed commander of the "Heyl Mada" – scientific research and development corps. His brother, Aharon Katzir, chairman of the Department of Polymer Research at Weizmann Institute, was murdered in the Lod Airport Massacre. Katzir was married to Nina, born in Poland, who died in 1986. As an English teacher, Nina developed a unique method for teaching language. As the president's wife, she introduced the custom of inviting children books' authors and their young readers to the President's Residence. She established the Nurit Katzir Jerusalem Theater Center in 1978 in memory of their deceased daughter, Nurit, who died from accidental carbon monoxide exposure and another daughter, Irit, killed herself. They had a son, Meir, and three grandchildren. Katzir died on 30 May 2009 at his home in Rehovot.
In 1973, Golda Meir contacted Katzir at Harvard University, asking him to accept the presidency. He hebraicized his family name to Katzir, which means 'harvest'. On 10 March 1973, Katzir was elected by the Knesset to serve as the fourth President of Israel. He received 66 votes to 41 cast in favour of his opponent Ephraim Urbach and he assumed office on 24 May 1973. In November 1977, he hosted President Anwar Sadat of Egypt in the first ever official visit of an Arabhead of state. In 1978, he declined to stand for a second term due to his wife's illness, and was succeeded by Yitzhak Navon. After stepping down as President, he returned to his scientific work.
