French chemist Henri B Kagan and Japanese scientist Kenso Soai have won the 2026 Nobel Prize in Chemistry for solving a century-old puzzle: how chemical reactions can produce only one of two possible mirror-image forms of a molecule.

 

The Royal Swedish Academy of Sciences awarded the prize “for the discovery of non-linear effects and autocatalysis in asymmetric organic synthesis.”

 

Their work helps explain homochirality, a defining feature of life’s chemistry. Molecules such as amino acids can exist in two mirror-image forms, but living organisms overwhelmingly use only one.

 

For decades, chemists struggled to understand how this chemical “handedness” could emerge. Ordinary reactions typically produced equal amounts of both mirror images. Controlling the outcome is also crucial in drug development, where the two forms of a molecule can have very different effects in the body.

 

"Henri Kagan and Kenso Soai have provided a solution to a chemical mystery that is over a century old: how homochirality can emerge spontaneously. The chemical reactions they have developed are spectacular,” says Heiner Linke, chair of the Nobel Committee for Chemistry.

 

Kagan made the first major breakthrough in 1986, discovering a new way to manipulate chemical reactions and produce a much larger excess of one mirror image than previously thought possible.

 

Soai took the next decisive step. In 1995, he described a reaction with the potential to become homochiral. In 2003, he succeeded in producing only one of the two possible mirror images.

 

Other than life itself, no one had previously achieved this feat.

 

The discoveries transformed scientists’ understanding of how chemical asymmetry can arise and gave chemists powerful new tools for designing reactions, including those used to manufacture pharmaceuticals.

 

Kagan, born in 1930 in France, is Professor Emeritus at Université Paris-Sud. Soai, born in 1950 in Hiroshima, Japan, is Professor Emeritus at Tokyo University of Science.

 

The two laureates will share the 12 million Swedish kronor Nobel Prize in Chemistry.