The invention relates to a process for preparing 5-sulfonamido-benzofuran derivatives of general formula: formula (I) in which R represents an alkyl or aryl group and R1 and R2 represent hydrogen or an alkyl or aryl group. According to the invention, the compounds of formula I are prepared by coupling a benzofuran derivative of general formula II, where X represents chlorine, bromine or iodine or a sulfonate group: formula (II) with a sulfonamide derivative of formula R—SO2—NH2, in the presence of a basic agent and of a catalyst system formed from a complex between a palladium compound and a ligand.