Microwave chemistry and microwave material processing have attracted the interest of scientists and engineers in the last decades, but applications have remained limited to vulcanizing of rubber, pre-drying of ceramics, drying of foods, etc., which all depend on the special heating mode independent of thermal conduction. Recently, researches in microwave technology have again investigated the possibility of a new technique of reaction control resulting in higher reaction rates, shorter reaction times, and energy saving. The huge demand for highly efficient recycling of carbon and hydrogen sources has emphasized the importance of R&D on green chemical processes for the production of energy carriers and conversion of carbon resources. To overcome the constraints of thermal equilibrium, development of chemical and separation methodology will be important based on the irreversibility or high selectivity enabled by controlling the kinetics or non-equilibrium state. Microwave technology has a potential to realize such processes.

This special issue includes both review papers and regular papers covering inorganic chemistry, organic chemistry, materials science, catalysis, and biomass chemistry. Invited articles describe the characteristics of "microwave special effects" which have long been attractive but mysterious subjects of controversy and discussion. All authors were invited from academia and corporate members belonging to the 188 Committee (Electromagnetic Field-Excited Reaction Fields) of the University-Industry Research Committees supported by the Japan Society for Promotion of Science of which I am a current chair. I hope that this issue will inform the members of the Japan Petroleum Institute and related researchers/engineers of the current situation in microwave technology. Finally, I express my sincere thanks to the editorial board of the journal and the secretariat of the society.