The presence of fluorine atoms on the alkyl chains hinders gas adsorption; consequently, the measured surface area of this MOF is very low. In order to obtain a fluorinated material with acceptable surface area, MOF-801 was taken as starting point to carry out PSE in aqueous solutions with variable amounts of H2TFS. In the two exchanged materials, the amount of fluorinated linker is about the same despite the different concentrations used in the synthesis, and it is most likely placed in the precursor defective sites. This suggests that the post-synthetic exchange involves only acetate and not fumarate.