The parity plots of the pre-trained and fine-tuned models are presented in Figure for the experimental test set. It can be seen that the predictions on the H-abstraction reactions are substantially improved after fine-tuning the model. This was expected as the fine-tuning set primarily comprises H-abstraction reactions. The fine-tuned models also have slightly improved predictions on β-scission reactions. The models, on the contrary, have relatively poor performance on Reactions 9, 11, 12, and 13 (see Supporting Information Table for details on the reactions). Notably, the fine-tuned model with the RP-solv feature exhibits high deviations for Reaction 12, which is a nucleophilic addition reaction. Our former study revealed that while varying the level of theory had little impact on log 10 (k rel ) calculations for most reactions, Reaction 12 displayed particularly high sensitivity to the levels of theory used in calculations. Therefore, it is possible that the RP-solv features (∆G solv and ∆H solv of reactants and products) calculated for Reaction 12 were not accurate enough and led to higher errors.