Nurex process which has been developed by Nippon Mining Co., Ltd, and has the capacity of 40, 000 t/y production of normal paraffins from kerosene and gas oil by urea adduction technique, is now in successfull operation for about one year. In this paper the author has described about the recent theories and principles concerning with the urea adduction, refering to the 26 papers, and refered also characteristics of Nurex process.