The kinetics fo production of proton‐bound dimers of dimethyl‐ and diisopropyl‐tartrate were analyzed were analyzed by the method of initial slopes. From the pressure dependence of the apparent bimolecular rate constatn, the back‐dissociation rate and radiative stabilization of the intermediate excited collision complex was calculated. The back‐dissociation (10.3 and 2.8 × 10 3s−1) and radiative (8.2 and 7.1 s−1) rates are compared to literature values for functionally similar acetone. In contrast to acetone these dimers exhibit a back‐dissociation reaction to regenerate the monomer species. These results can be taken to imply a lower binding energy in these dimers due to steric effects. Competing reactions to form ions of m/z 145 and 235 were also observed for the dimethyl and diisopropyl ester, respectively.