A prototype system is described for the large scale, continuous production of nanophase metals, metal oxides, and other nanophase materials using the polyol process. The polyol process employs an organic solvent such as ethylene glycol to reduce a metal oxide/metal salt at high temperature to the metal oxide or metal. The system employs a 6 kW, 2.45 GHz microwave source to rapidly heat the continuously flowing solution to a desired process temperature as it flows through a silica tube placed along the center line of a section of waveguide.