NOTT-401 was found to be a highly stable adsorbent for SO2 and CO with excellent cyclability and a straightforward regeneration at room temperature. Moreover, the preferential CO binding sites within the MOF material have been identified by experimental in situ DRIFT spectroscopy coupled with DFT and QTAIM calculations. Such preferential CO adsorption sites were correlated to identify the most significant SO2 interactions within NOTT-401. This study sheds light on the role of the thiophene and hydroxo functionality, for a MOF material, in the binding of SO2 or CO.