The performance of a prototype novel gas fluidized bed stirred media mill was compared with that of conventional stirred media mills. The gas fluidized bed stirred media mill concept is thought to offer the advantages of reduced viscous dissipation of energy into the suspending fluid, continuous removal of product fines, and comminution in a dry environment. The test results confirm reduced power consumption relative to the liquid suspension stirred media mill. The energy efficiency (m(2) of new surface generated per kilowatt hour of milling energy supplied) of the prototype was found to be less than that of the liquid suspension mill, but it was greater than when the mill was operated without liquid suspension or air fluidization. Resources did not permit optimization of the mechanical design or operating conditions of the mill. With more work devoted to the concept, higher efficiencies could probably be realized.