Odd Hassel was a Norweigan physical chemist and Nobel Laureate.

He was born in Kristiania (now Oslo), 17 May 1897. His parents were Ernst Hassel, a gynaecologist, and Mathilde née Klaveness.

In 1915 he entered Oslo University where he studied mathematics, physics and chemistry andd graduated in 1920. After a year of leisure in southern Europe he went to Germany where he first spent some time in Munich in the laboratory of Professor Kasimir Fajans. His work there led to the development of adsorption indicators . After moving to Berlin he worked at the Kaiser Wilhelm Institute, carrying out X-ray crystallographic work. During that time he obtained, with the help of Fritz Haber, a Rockefeller Fellowship . In 1924 he obtained his PhD from the Berlin University. From 1925 to 1964 he worked at the University of Oslo in various functions on physical chemistry.

Hassel's main interest during the first years at the University dealt with inorganic chemistry, but from 1930 onwards his work was concentrated on problems connected with molecular structure, particularly the structure of cyclohexane and its derivatives. He introduced to Norway the measurements of electric dipole moments and electron diffraction by vapours. A short paper on the conformations of cyclohexane had just been published in a Norwegian journal when Hassel was arrested by Norwegian Nazis. Released in November 1944 he found the institute almost deserted.

During the early 1950s Hassel investigated the structure of charge-transfer compounds, and after some years work he was able to set up rules for the geometry of this kind of compound.

He died 11 May 1981.