Upon the completion of 130 water sorption-desorption cycles, we re-analysed COF-SO3H using FTIR, XPS, and PXRD. COF-SO3H remained unchanged from the pristine material in all cases (Figure ). Given the onset of water uptake at <5% RH and the apparent stability after 130 adsorption-desorption cycles, COF-SO3H shows promise for AWH in extreme environments.