Microwave radiation is a relatively new energy source, which has considerable potential for various applications in mineral processing and extractive metallurgy. However, the strengths of the interaction of the microwave radiation with the materials of interest are largely unknown. Additionally, in contrast to the aqueous solutions used in hydrometallurgy, the microwave interaction with the heterogeneous solids used in pyrometallurgical processes is difficult to model from fundamentals. Since the microwave heating characteristics of most of the materials cannot be predicted, research is being performed to determine the underlying factors which govern the microwave response of ores, concentrates, reducing agents and other feedstocks used in pyrometallurgical processes. In the present research, the techniques used to measure the microwave coupling characteristics are outlined and the application of these techniques to some relevant pyrometallurgical materials is reviewed. (C) 2009 Elsevier Ltd. All rights reserved.