In this study, we applied the concept of TS structural similarity to clustering reaction steps on either Cu or Pd, revealing more accurate correlations between activation and reaction energies (Figure ; see Section S2 for details of the linear fitting procedure). For hydrogenation steps (Figure ), we identify two TS types where, formally, H • or H -bind to surface intermediates (see charge analysis in Section S6). The pink data points in Figure correspond to hydrogen associating with carbon in a tetrahedral sp 3 -like TS, leading to sp 3 products in hydrogenations of CH3*, CH2COOH*, CH3CHOH*, etc. (here and below, the reacting atom is given in bold). Some seemingly sp 2 centers like CH2* lay within this BEP due to the tetrahedral TS in which the intermediate binds to two metal atoms in sp 3 -like geometry. The linear regression of activation and reaction energies for these steps yields low RMSD values of 0.12 eV for Cu and 0.06 eV for Pd, which is well below DFT accuracy benchmarks. Notably, CH3* hydrogenation on Cu is an outlier (∆𝐺 ‡ = 1.15 eV, Figure , left), possibly because CH3* partially detaches from the nanoparticle in TS leading to physisorbed CH4, unlike in other steps where the products remain surface-bound.