Aryl diazonium salts react with a mixture of merourio ohloride, diethyl phosphito, cuprio ohloride and acetono at room temperature to give corresponding arplmercurio chlorides in high yields without isolation of the diazonium morcurichlorides.Thirty one arylmerourio chlorides, including five now compounds, were prepared by this method.Preliminary investigation indicates that the reaotion probably proceeds by free raducal mechanism.