The ring-opening cationic polymerization of 2-ethyl-2-oxazoline was performed in a single-mode micro-wave reactor as the first example of a microwave-assisted living polymerization. The observed increase in reaction rates by a factor of 350 (6h --> 1min) in the range from 80 to 190degreesC could be attributed solely to a temperature effect as was clearly shown by control experiments and the determined activation energy. Because of the homogenous microwave irradiation, the polymerization could be performed in bulk or with drastically reduced solvent ratios (green chemistry).