Rh(II)-catalyzed oxidative coupling of aldehydes and sulfonamides has been developed to provide N -sulfonylcarboxamides in one step. A variety of sulfonamides were found to react with aromatic and aliphatic aldehydes to afford the desired products in good to excellent yields. Mechanistic data, including kinetic isotope effect experiments, suggest that the transformation proceeds through a concerted asynchronous nitrene insertion into an aldehydic hydrogen.