A method for safety investigations of microreactors and microstructured components for the operation inside the explosion region is presented. Microstructured reactors are not inherently safe, although the range of safe process conditions is wider than that of conventional reactors. The explosion region can be narrowed due to the microstructure. Using the example of ethylene-oxygen mixtures and ethylene-nitrous oxide mixtures it is demonstrated that the so called lambda/3-rule can be applied with respect to the propagation of detonations in microcapillaries. Furthermore, first results of the investigation of the propagation of explosions in a microreactor with a rectangular flow channel are presented.