Although microwave enhanced chemistry has become an established research topic, a significant knowledge gap exists with respect to the electromagnetic interactions. This paper aims to address this gap, in particular regarding to small and microstructured processing systems. By means of relatively simple demonstrations, key electromagnetics aspects are highlighted, pointing out the restricted control over operating conditions in familiar microwave systems. In response to these limitations, a radically different approach is presented in the shape of the coaxial traveling microwave multichannel reactor concept. Numerical simulations show that this concept enables controlled and optimized microwave processing. (C) 2014 Elsevier B.V. All rights reserved.