Acyloin condensation is a reductive coupling of two carboxylic esters using metallic sodium to yield an α-hydroxyketone, also known as an acyloin.

The reaction is most successful when R is aliphatic and inert. The reaction is performed in aprotic solvents with a high boiling point, such as benzene and toluene. The use of protic solvents results in the Bouveault-Blanc reduction of the separate esters rather than condensation. Depending on ring size and steric properties, but independent from high dilution, the acyloin condensation of diesters favours intramolecular cyclisation over intermolecular polymerisation.