Sulfonyl chlorides react with water to give the corresponding sulfonic acid:
These compounds react readily with many other nucleophiles as well, most notably alcohols and amines (see Hinsberg reaction). If the nucleophile is an alcohol, the product is a sulfonate ester; if it is an amine, the product is a sulfonamide. Using sodium sulfite as the nucleophilic reagent, p-toluenesulfonyl chloride is converted to its sulfinate salt, .  Chlorosulfonated alkanes are susceptible to crosslinking via reactions with various nucleophiles.
Sulfonyl chlorides readily undergo Friedel–Crafts reactions with arenes giving sulfones, for example:
The desulfonation of arylsulfonyl chlorides provides a route to aryl chlorides:
1,2,4-Trichlorobenzene is made industrially in this way.
Treatment of alkanesulfonyl chlorides having α-hydrogens with amine bases can give sulfenes, highly unstable species that can be trapped:
Sulfonamides can be prepared by reaction of sulfonyl chlorides with amines:  
A readily available sulfonyl chloride source is tosyl chloride.
Reduction with tetrathiotungstate ions () induces dimerization to the disulfide.