Abstract The non‐enzymic glycation of hemoglobin is catalyzed by 3‐phosphoglycerate, 2‐phosphoglycerate and 2‐glycerolphosphate, but not by sodium propionate. Solvent isotope effects were determined ( k / k ). Catalysis by 3‐phosphoglycerate, 2‐phosphoglycerate and 2‐glycerolphosphate, the observer solvent isotope effect of unity, and flat proton inventory tend to suggest that the proton abstraction step of the Amadori rearrangement by 3‐phosphoglycerate, 2‐phosphoglycerate and 2‐glycerolphosphate is the rate‐determining step in the non‐enzymatic glycation of hemoglobin. The solvent isotope effect of unity, and a flat proton inventory for sodium propionate are indicative that a functional group on the hemoglobin is the proton‐abstracting base in the Amadori rearrangement. Copyright © 2002 John Wiley & Sons, Ltd.