In organic chemistry, a group transfer reaction is a pericyclic process where one or more groups of atoms is transferred from a molecule to another. Unlike other pericylic reaction classes, group transfer reactions do not have a specific conversion of pi bonds into sigma bonds or vice versa. Group transfer reactions are less frequently encountered processes and they can be sometimes confused with Diels–Alder cycloadditions. Like all pericyclic reactions, they must obey the Woodward–Hoffmann rules.
The best known group transfer reaction is the ene reaction.