Acid-base chemistry is foundational to many chemical and biological processes. As chemists we often define acid strength in terms of acid dissociation equilibria, a description which is well suited to aqueous solution where acid behavior is mediated by the extended hydrogen (H)-bonding network of liquid water. This description becomes complicated when considering solid acid sites in porous materials, since the extended H-bonding network of water is disrupted under confinement. Zeolites provide an ideal system for studying this behavior, where Brønsted acid sites (BAS) are present inside the regular, molecule sized pores of these materials. Since zeolites are widely used acid catalysts, a molecular description of their acidity is highly relevant to several industrial processes including emerging bio renewable processes where water is often present. However, many molecular details of zeolite water interactions are not well understood. Central questions regarding the protonation state of the hydrated zeolite system, the extent and structure of water’s disrupted H-bonding network inside small pores, and the evolution of these properties with increasing hydration had not been previously addressed experimentally.The structure and protonation state of water at zeolite Brønsted acid sites were investigated over a wide range of hydration per BAS using infrared (IR) spectroscopy, which is sensitive to the H-bonding environment of water molecules. Several structural characteristics including anharmonic couplings, excited state energies, and bond orientations were revealed with femtosecond two-dimensional IR (2D IR) spectroscopy, which had not been previously applied to this system. Measuring high quality nonlinear spectra required several adaptations to the experimental design to mitigate artifacts from highly scattering zeolite particles. These spectroscopic studies present a detailed experimental characterization of water and protons under tight confinement near solid acid sites. When a single water molecule is adsorbed at the BAS, the proton remains localized on the acid site displaying an IR spectrum with two broad bands centered near 2500 cm-1 and 2850 cm-1. While the origin of this doublet feature has been a longstanding mystery, the 2D IR spectrum provides new experimental evidence to constrain the problem. Based on the relative frequencies and intensities of excited state absorptions, we propose a model proton transfer potential with excited state tunneling, which is consistent with the experiment. As the hydration increases, new vibrational features appear corresponding to hydrated protons and water O-H bonds in various environments. Analysis of these features showed that the BAS is deprotonated in the presence of two or more water molecules, with the hydration saturating at approximately 8 H2O molecules per BAS. Finally, while 2D IR spectroscopy has proven to be an insightful tool for studying the structure and dynamics of water and protons, some information content is limited by the broad linewidths of these systems – relative to the bandwidth of available mid IR laser pulses. To expand our 2D IR capabilities, we report the design and operation of a new light source which extends the mid IR pulse bandwidth to ~1000 cm-1 with sufficient energy to excite molecular vibrations. The source is implemented in 2D IR experiments, demonstrating simultaneous excitation and detection across a broad range of mid IR frequencies.