Kagan and Soai win 2026 Nobel Prize in Chemistry for work on molecular handedness

French chemist Henri B. Kagan and Japanese chemist Kenso Soai have won the 2026 Nobel Prize in Chemistry for discoveries explaining how chemical reactions can favor one of two 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.” Kagan and Soai will share the 12 million Swedish kronor prize equally.

Many molecules exist in two forms, known as enantiomers, that contain the same atoms but are arranged like left and right hands. Biological systems often use only one form, a phenomenon called homochirality. The distinction is important in pharmaceutical manufacturing because two versions of the same chiral drug can interact differently with proteins, enzymes and receptors in the body.

In 1986, Kagan and his team demonstrated a non-linear effect in which interactions among chiral catalysts could disproportionately increase the amount of one molecular form produced by a reaction. The finding helped chemists analyze reaction mechanisms and improve methods for making selected enantiomers.

Soai and his colleagues showed in 1995 that a chiral molecule could catalyze the production of more molecules with the same handedness. In the resulting “Soai reaction,” a very small initial imbalance can be amplified through repeated cycles until one form strongly predominates.

Nobel chemistry committee chair Heiner Linke said their work offered a solution to the century-old question of how homochirality can arise spontaneously. Soai, a professor emeritus at Tokyo University of Science, said he was grocery shopping when notified of the award. Kagan is a professor emeritus at the former Université Paris-Sud.