This research will elaborate a new approach to the production of simple tubular polymeric millireactors and polymer millireactors with static mixers using additive production technologies in order to facilitate the study of process intensification. Millireactors of different channel dimensions have been manufactured, and static mixers added to the successfully manufactured millireactors. The manufacturing principle – addition of material in layers – allows the formation of complex geometric structures within the channel. Static mixers create larger interphase surfaces between reactants, so the applicability of millireactors to multiphase, immiscible systems will also be tested. For the model reaction, transesterification of sunflower oil into FAME is selected. Fast conversion of FAME which is causative consequence of the efficient mass and energy transfer will be monitored by nuclear magnetic resonance (1H NMR), gas chromatography (GC), and infrared spectroscopy (FTIR). The obtained results represent a contribution to the use of milireactors and milireactors with static mixers, as well as reactors with oscillating fluid flow, as a replacement for well-known microreactors in which the production volume is smaller and the pressure drop is larger than in milireactors. Flow patterns, mass transfer and dimensionless numbers were analyzied in all successfully constructed reactor systems. The results point to the fact that longer retention times in millireactors give higher conversions, as well as higher temperatures and narrower channels have been. Due to the different mixing mechanism greater process intensification is acheived in a tube baffled reactor in comparison with milireactors with baffles. In the last part of the research, attention was paid to the physical and chemical properties of the materials used for 3D printing to determine whether such reactor systems could be applied in other chemical syntheses as well. For this purpose thermal properties of commercially available polymeric materials were examined, as well as their free surface energy and swelling resistance in various liquids which the produced millireactors could come into contact with.