Kagan and Soai win 2026 chemistry Nobel for solving molecular mystery

France's Henri Kagan and Japan's Kenso Soai won the 2026 Nobel Prize in Chemistry on Wednesday for explaining why only one form of certain molecules appears in nature. Their discovery is decisive for the manufacture of pharmaceuticals.

Why did Kagan and Soai win the Nobel Prize in Chemistry?

The two chemists showed how one mirror-image form of a molecule can emerge spontaneously, solving a puzzle more than a century old. In the 1980s, Kagan found a way to create an excess of one form. Soai published the design for a potentially homochiral reaction in 1995 and succeeded in 2003.

The jury honored the pair "for the discovery of non-linear effects and autocatalysis in asymmetric organic synthesis".

What is homochirality in chemistry?

Like hands, molecules such as amino acids exist as two mirrored variants. Only one of them is found in the proteins in the body's cells, while the other is rarely found in nature. The Royal Swedish Academy of Sciences calls this phenomenon "homochirality".

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

Why does molecular handedness matter for drugs?

The academy likened the problem to a locksmith creating keys to order who always produces two mirrored variants. "Only one of them fits the lock, and the lock can be damaged if your customers try to unlock it with the other key."

The thalidomide scandal of the late 1950s and early 1960s showed the danger of using the wrong version, when thousands of children were born with birth defects. "When researchers analyzed what had happened, they realized that it was the active substance's mirror image that caused the harm," the academy said.

Phillip Broadwith, an editor at the Royal Society of Chemistry's Chemistry World magazine, said the duo's work "goes to the very fundamental level of understanding how we can control which 'hand' of a molecule we make". That control is "crucial for making things like drugs or even flavors and fragrances", he said.

Broadwith added that the work also helps explain a possible way that all the chiral molecules on earth, including proteins, sugars and biomolecules, settled into one specific handedness rather than the other. The academy described the Soai reaction as "one of the most elegant chemical experiments ever conducted".

Who are Henri Kagan and Kenso Soai?

Kagan, 95, is professor emeritus at the Universite Paris-Saclay in France. Soai, 76, is a professor at Tokyo University of Science. Soai was out shopping when he received the call from Stockholm and said it was one of "the most exciting days in my life", when reached by the Nobel Foundation during Wednesday's press conference.

The Academy had not been able to reach Kagan before the announcement. French President Emmanuel Macron congratulated him on X, calling his achievement "a tremendous source of pride for the country".

Kagan had previously missed out on the prize. In 2001, the chemistry prize went to William Knowles, Ryoji Noyori and Barry Sharpless for pioneering work in asymmetric catalysis. That sparked controversy, with many French chemists outraged by the absence of the man regarded internationally as the "father" of the technique.

Which Nobel Prizes have been announced in 2026?

The chemistry prize follows the physics prize, which on Tuesday honored Belgian physicist Francis Halzen for work using Antarctic ice to capture particles originating in the distant cosmos. On Monday, the medicine prize went to US psychiatrist and neurologist Karl Deisseroth and German scientists Peter Hegemann and Georg Nagel.

The literature laureate will be revealed on Thursday, and the peace prize is due on Friday. The economics prize wraps up the Nobel season on October 12.