Abstract Microwave technology is gaining an essential relevance for heating processes at an industrial level due to its improvements in energy savings and product quality. Nevertheless, the microwave system design and material selection during the applications are key points that play an essential role in the successful performance of the process, its implementation, and its operation. The proper function of the microwave highly depends on the design and a good selection of the materials. There are different kinds of materials for microwave applications such as transparent (not able to be heated), semi-transparent (low absorption of microwaves), and susceptor (materials with high capacity to absorb microwaves and transform them into thermal energy). This investigation shows the way each of these materials converts microwaves into heat. Both heat transfer and exergy transfer analyses are presented, focused on those materials with high interactions with microwaves (susceptors). The heat transfer studies demonstrated the way microwaves are transformed into heat, and the exergy analysis shows the quality of those transformations. Exergy transfer analysis of microwave heating systems sheds light on the efficiency of the energy transformation taking place during microwave processing. Consequently, by combining studies of microwavable materials with exergy transfer analysis, conclusions for new microwave designs can be reached, improving this promising technology's final performance. In this sense, this work provides an easy method to determine different materials' behavior under microwave effects.