With the rise in atmospheric CO2 levels contributing to global climate change, 1-3 CO2 capture is an active area of research. CO2 capture technologies can broadly be divided into absorption and adsorption technologies. Absorption technologies involve the absorption of CO2 by a liquidphase solvent, such as monoethanolamine (MEA), or ionic liquids. Adsorption technologies use solid adsorbents to sequester CO2 by physically adsorbing it to the surface, i.e., by Van der Waals interactions, or chemically adsorbing it to the surface, as is common in aminefunctionalized solids. One adsorbent material, Calgary Framework 20 (CALF-20), is a MOF with excellent thermal and hydrolytic stability, high CO2 capacity, and selectivity for CO2 over H2O and N2. 1 CALF-20 is stable to steam for more than 450,000 cycles 1 and does not lose surface area after adsorbing water at 175 ºC and 672 kPa. These features make it an attractive alternative to amine-based CO2 adsorbents, and as such, it has garnered significant attention in the literature. Specifically, CALF-20 is a Zn-based MOF [Zn2(1,2,4-triazolate)2(oxalate)], which is commercially scalable, 1 and the hydrophobic nature of the surface eliminates the need for a drying step before CO2 capture. CALF-20 adsorbs CO2 weakly, with a binding energy of around -35 kJ/mol, 1 which in many cases is lower than the binding energies of amine-functionalized, chemisorptive MOFs (-130 to -180 kJ/mol) thereby providing an energetic advantage during desorption when compared to materials that strongly bind CO2. Though it adsorbs CO2 weakly, it still provides excellent CO2 capacity of 1.3 and 2.8 mmol/g at 4% and 13% CO2, respectively, which are relevant postcombustion CO2 capture concentrations. Also, because the MOF is stable to steam, CO2 can be desorbed by directly applying steam to the MOF. As a result of these adsorption behaviors, significant effort has been applied to understanding the thermodynamic capacity of CALF-20 via isotherm and breakthrough studies, including efforts to quantify the binary CO2/H2O adsorption equilibrium. While the isotherm is important, understanding gas diffusion kinetics is also necessary when applying adsorbents in cyclic adsorption applications, such as pressure swing adsorption (PSA) and temperature swing adsorption (TSA). Adsorption rates are important in these applications because the rate at which adsorbate molecules diffuse through an adsorbent can dramatically affect the productivity of a process, enabling optimal regeneration cycling to best exploit the capacity of an adsorption system. However, experimental adsorption kinetics for CO2 and H2O on CALF-20 have mainly been examined in a limited capacity, typically via breakthrough studies. Extraction of diffusion data from breakthrough measurements is challenging because heat effects, and bed conditions (flow rate, temperature, pressure drop, dispersion) and other transport behaviors must be accounted for carefully. Also, breakthrough, as well as uptake methods, do not allow for the identification of diffusion mechanisms, but rather a model is assumed. Beyond experimental methods, computational methods have also been applied to understand diffusion in various porous materials, including CALF-20. For example, Ho and Paesani showed that H2O and CO2 compete for the same binding sites and slow their diffusion in a binary scenario. Magnin et al. found that the self-and corrected diffusivities of CO2 and H2O in CALF-20 are of the same order of magnitude and that CO2 uptake slows down as water loading increases. simulated the effects of shaping CALF-20 with polymer binders and found no impact on the self-diffusion of CO2 in CALF-20. These results provide fundamental insight into the material, but in application, the limiting diffusion length and time scales are typically larger than those simulated using molecular dynamics. Also, the transport diffusivity is of practical concern since this gives the flux for a system that is not in equilibrium, while self-diffusion, as has been simulated for this system, is the rate of diffusion of adsorbed molecules at equilibrium as they follow a random-walk process . Various experimental techniques are available for measuring the diffusion rates of gases in porous materials. These can be broadly divided into microscopic methods, such as quasi-elastic neutron scattering (QENS) and pulsed field gradient (PFG) NMR, which in general quantify the self-diffusion, or , and macroscopic techniques, such as transient uptake, zero-length column (ZLC) chromatography, and frequency response (FR). Macroscopic techniques are helpful because they quantify the transport diffusion, which describes diffusion under nonequilibrium conditions. They also provide adsorption rates relevant to the design and modeling of adsorption cycles.