The experimental data set consists of 165 relative rate constants (k rel ) for 15 neutral reactions and 49 solvents from 273 K to 392 K. None of the experimental reactions appear in the pre-training and fine-tuning sets, and therefore these data serve as a reaction split test set for the final model evaluation. The reactions are depicted in Supporting Information Table , and they include 2 β-scission, 5 H-abstraction, 3 Diels-Alder, and 5 other types of reactions. The reactions involve H, C, N, O, and S atoms and have up to 22 heavy atoms, which are much larger than the reactions found in the pre-training and fine-tuning sets. The atom mappings of these reactions are obtained using the tool from Ref 56, and incorrect atom mappings are then manually fixed. The errors on the experimental test set are computed in both log 10 (k rel ) and ∆G ‡ rel units, where the ∆G ‡ rel error is calculated as follows: