Microwave processesing is a relatively new technique for chemical syntheses, and it is proving to be more widely applicable than could have been imagined even just rive years ago. After a brief introduction to the theory, this article presents the advantages of microwave dielectric heating and discusses applications to solid-state oxides. superconductors, fine metal powders, and semiconductors. The speed of the reaction is often impressive. and the phenomenon of ''thermal runaway'', despite its name, can be helpful rather than a nuisance.