RationaleRecently N‐Fluoroarenesulfonamides (ArSO2NHF) were found to be promising precursors for the preparation of N‐fluorobenzenesulfonimide derivatives without applying F2. However, very few studies have discussed the mass spectrometric behaviors of ArSO2NHF with N–F structure.MethodsIn this article, we applied high‐resolution electrospray ionization tandem mass spectrometry (HR‐ESI‐MS/MS) to study the effect on the mass spectrometric behaviors of ArSO2NHF after the introduction of the F‐atom to the N‐atom of ArSO2NH2.ResultsHigh‐resolution electrospray ionization mass spectrometry (HR‐ESI‐MS) experiments showed that ArSO2NHF produced only good signals in negative ion mode, and the dominating product ion SO2F− at m/z 83 was observed in all HR‐ESI‐MS/MS of ArSO2NF− with different substituents in the Ar group. The formation of the product ion SO2F− was proof of the gas‐phase F‐atom migration rearrangement from the N‐atom to the S‐atom in ESI‐MS/MS of ArSO2NF−.ConclusionTo fully explain the gas‐phase reaction mechanism from ArSO2NF− to SO2F−, we studied the HR‐ESI‐MS/MS of deprotonated ArSO2NHF and also performed theoretical calculations. Both results confirmed that ArSO2NF− first underwent Smiles rearrangement to yield intermediate I (INT1) ArNFSO2−, and then the F‐atom of ArNFSO2− migrated from the N‐atom to the S‐atom to form intermediate II (INT2) ArN−SO2F, which finally dissociated to SO2F− at m/z 83 with loss of a neutral nitrene (ArN). All these results showed that the formation of the product ion SO2F− from ArSO2NF− was a common and intrinsic gas‐phase reactivity of ArSO2NF−.