Benzenesulfonyl chloride is an organosulfur compound with the formula C₆H₅SO₂Cl. It is a colourless viscous oil that dissolves in organic solvents, but reacts with compounds containing reactive N-H and O-H bonds. It is mainly used to prepare sulfonamides and sulfonate esters by reactions with amines and alcohols, respectively. The closely related compound toluenesulfonyl chloride is often preferred analogue because it is a solid at room temperature and easier to handle.