To further test the GNN models, we test against the values in ExpSolv/nonoverlap dataset, a compilation of ∆G * solv (A -) values that only uses experimental data for the thermodynamics (i.e., no properties from quantum chemical calculations). In ExpSolv/nonoverlap, the ∆G o acid, gas (AH) values were obtained from NIST/nonoverlap 51 and the neutral solvation free energies are from dGsolvDB3/nonoverlap. The pK a data in both ExpSolv/nonoverlap and D2A-dGsolv-anion/test are the same (from D2A-pKa), and hence there is no error con-tribution associated with those pK a values. This test set includes 8 values, all in water. Figure depicts good performance of the model on ExpSolv/nonoverlap, with an RMSE of 1.17 kcal mol -1 in water. The errors are slightly lower than the uncertainties of ∆G * solv (A -) shown in Figure (RMSE values of 1.49 kcal mol -1 in water, comparing D2A-dGsolv-anion to ExpSolv/overlap). As shown in Figure , the COSMO-RS method again performs worse than the direct ML model. Note that the COSMO-RS values were shifted by a parameter δ that minimizes the error of the COSMO-RS errors against ExpSolv/overlap data, to account for systematic misalignments in energy scales.