The fine-tuning data set has 542,833 reaction-solvent pairs with 1870 unique reactions including both forward and reverse directions and 295 solvents. The geometry optimizations were performed at the M06-2X/cc-pVTZ level of theory in the original work by Harms et al. for these reactions. The data set contains three specific reaction types: bimolecular hydrogen abstraction (H-abstraction), unimolecular hydrogen migration (H-migration), and radical addition to a multiple bond (R-addition). These are neutral, free radical reactions that are ubiquitous in both gas and liquid phase systems. The reaction templates are illustrated in the Supporting Information Figure . In total, there are 1402 H-abstraction, 146 H-migration, and 322 R-addition reactions. The reactions involve maximum 10 heavy atoms and include H, C, and O atoms. The histograms and statistics of the data are presented in Supporting Information Figure . The ∆∆G ‡ solv and ∆∆H ‡ solv have absolute average values of 1.40 and 2.32 kcal/mol, respectively, with standard deviations of 1.91 and 3.17 kcal/mol. Similar to the pre-training set, only a subset of the fine-tuning data was chosen for the model. We sampled around 25 solvents per each reaction semi-randomly with more weights on polar solvents in order to include more data with stronger solvent effects. A total of 46,122 data points were selected, and all reactions and solvents appear in the chosen set at least once. The detailed data sampling method is explained in Supporting Information Section S2.