The observed H-S compensation effects via epoxidation catalysis (i.e., ΔH excess and ΔS excess ) are quantitatively consistent with the experimentally measured changes in enthalpies and entropies associated with disrupting H 2 O solvent structures (i.e., ΔH HB and ΔS HB ; Fig. ) within these same pore environments. Figure shows the H-S compensation that originates from ΔH HB and ΔS HB measured independently via IR spectroscopy (vide supra) within bulk H 2 O and H 2 O filled pores of Ti-zeolite catalysts. The excellent agreement between kinetic and spectroscopic measurements testifies to the control that solvent reorganization processes hold over the stability of adsorbates and reactive intermediates (e.g., epoxidation transition states). Significantly, the H-S compensation relationship obtained from analysis of IR spectra do not rely on the presence of a reactant and do not arise from measurements of specific catalytic reaction rates, therefore, these measurements strongly suggest that many other catalytic reactions will be governed by these same compensation phenomena within pores of these zeolites within aqueous solvents. Here, hydrogen bonded H 2 O molecules within confining pores (<1.3 nm) possess entropies that are much lower than bulk H 2 O as a result of the highly correlated molecular motion imparted by the surrounding pores. The disruption of these rigid H 2 O structures results in an entropic gain that is much larger than observed in bulk H 2 O, which leads to entropy-dominated decreases in the free energy of the system. In summary, this work gives compelling evidence for how the structure of intraporous solvent molecules and the reorganization of these solvent structures to accommodate the formation of reactive surface intermediates lead to consequential changes in the stability of reactive surface intermediates and large changes in the rates of reactions.