Following adsorption analysis, variable-temperature O2 and N2 desorption kinetics data were collected under reduced pressure (Figures 5c, S22, and S23), which revealed that O2 desorption from the material is more sluggish than N2 desorption. For example, after dosing with 1.0 mmol/g of each adsorbate at 298 K, half-life (t1/2) values extracted for O2 and N2 desorption were 161 and 16 s, respectively (Figure ), and this difference becomes even more pronounced upon lowering the temperature to 288 K (t1/2 values of 260 and 53 s, respectively; see Figures and). The desorption curves for both gases were fit using a pseudo-first order rate law and the resulting data used to calculate activation barriers for O2 and N2 desorption of Ea = 45(1) and 30(1) kJ/mol, respectively (Figure and Table ). Importantly, although the kinetics of O2 and N2 adsorption in Cu2.7-MFU-4l are similar and both gases are expected to be adsorb under conditions relevant to air capture, these results suggest that it may be possible to tailor the desorption conditions to isolate high-purity O2.