It is preferred that the diluent be substantially water-free, with a water concentration of less than about 50 ppmw (parts per million by weight of the diluent), more preferably less than about 5 ppmw, and most preferably less than 1 ppmw.It is preferred for the substantially water-free hydrocarbon feed to be hydrotreated before reforming in order to remove impurities such as nitrogen and sulfur.