An apparatus with rectangular product channels and static mixing elements for process intensification is investigated in terms of heat transfer and hydrodynamics. Herringbone-like static mixing elements increase the overall heat transfer coefficient significantly, and the stall angle was found to have a major influence on hydrodynamics and heat transfer. The knowledge of structural parameters of the mixing elements is crucial for apparatus design and prediction of the apparatus performance. A method to derive mean structural parameters from experimental results is presented.