Nobel Prize in Chemistry 2026 goes to Kagan and Soai for work on how one-handed molecules can emerge

The Royal Swedish Academy of Sciences announced on 7 October that the Nobel Prize in Chemistry 2026 goes to Henri B. Kagan of Université Paris-Sud, France, and Kenso Soai of Tokyo University of Science, Japan. The Academy cites them for discovering non-linear effects and autocatalysis in asymmetric organic synthesis, and says the pair found an answer to an old puzzle: how chemistry can come to favour just one of two mirror-image forms of a molecule. Kagan, born 1930 in Boulogne-Billancourt, is Professor Emeritus at the then Université Paris-Sud; Soai, born 1950 in Hiroshima, is Professor Emeritus at Tokyo University of Science. The prize of 12 million Swedish kronor will be divided equally between them. Nature reports that Soai was out shopping near his home when the call reached him.

Many molecules, amino acids among them, occur in two versions that mirror each other in the way a left and a right hand do. Living organisms, however, rely on only one of the two, a property chemists call homochirality; the Academy notes the term derives from the Greek for ‘same’ and ‘hand’. According to the Academy, when chemists ran reactions able to yield either form, their test tubes consistently ended up with equal amounts of both. That mattered in practice as well as in theory, the Academy explains, because for molecules meant to act on living beings, such as medicines, only one of the two forms has the desired effect. Nature gives an example: the DNA molecule has a right-handed form, whereas the amino acids found in living things are left-handed.

According to the Academy, Kagan made the first decisive advance in 1986 with a new way of steering chemical reactions, which let him obtain a larger surplus of one mirror image than chemists had believed possible. Nature describes this as showing that a slight imbalance in the handedness of a catalyst can be magnified in the products. Soai built on that. The Academy says a key 1995 publication described how he designed the first reaction with the potential to be homochiral, and that in 2003 he presented a reaction in which only one of the two mirror images formed, something it says nothing but life itself had managed before. In Soai's 1995 experiment, Nature reports, the reaction's product served as its own catalyst, and an initial excess of just 2% of one form grew to 87%.

Nature places the work in a longer line of research. It recalls that the theoretical physicist Charles Frank of the University of Bristol suggested in 1953 that a reaction able to make its own chiral catalyst would be self-reinforcing and let one mirror image win out. The 2001 chemistry laureates William Knowles, Ryoji Noyori and Barry Sharpless used chiral catalysts to push reactions towards one version of a molecule; according to Nature, Kagan and Soai went a step further by designing reactions that produce their own chiral catalyst, putting Frank's idea into practice. Bristol organic chemist Jonathan Clayden told Nature that Kagan demonstrated the principle and the Soai reaction supplied the first real example. Heiner Linke, chair of the Nobel Committee for Chemistry, said the laureates had resolved ‘a chemical mystery that is over a century old’.

Researchers quoted by Nature also see links to the origin of life. Furkan Öztürk, a researcher in prebiotic chemistry at the California Institute of Technology, told Nature the work has drawn wide interest from those trying to explain why biological molecules like amino acids and nucleic acids usually occur in a single chiral form. He cautions that the Soai reaction depends on conditions and reagents that sit poorly with early Earth, noting in particular that it cannot run in water, but he believes its basic principles still have much to teach. Oxford synthetic chemist Stephen Fletcher told Nature he could see the award reviving efforts to establish the reaction's biological relevance.