The kinetics of the reaction of 3‐deoxyhexosulose, DH, with mercaptoethanol, ME, and glutathione, GSH, resemble those of the DH‐sulphite reaction, but the stoichiometry of the DH‐thiol reaction is 1:2 unlike that of the DH‐sulphite reaction which is 1:1. However, the rate determining step in all these reactions is the spontaneous conversion of DH to a reactive intermediate, followed by a rapid reaction of this intermediate with the nucleophile. This is also true of the reaction between DH andN‐acetylcysteine, NAC, but this thiol is less reactive than ME or GSH and less than one mole of NAC reacts with each mole of DH. Evidence for instability of NAC at pH 5.5 is presented.