The focus of this study aimed the development of suitable synthetic methods for the preparation of low-risk nanomaterials. Two materials, namely iron oxide and silver nanoparticles were investigated and serve as part of the graduate program nanoToxCom for ecotoxicological studies. The production of the materials was performed on the basis of the so called polyol method. Depending on the synthesis parameters: temperature, reaction time, concentration and type of precursors, the physical parameters such as the particle shape and size could be controlled. Based on the micro-reaction technology, a fundamentally new concept was created for a high quality production of these nanomaterials. Finally, the usability of the nanomaterials was investigated in relation to appropriate applications like contrast media and the use as a homogeneous and heterogeneous catalyst