This study compares a two-phase flow through a foam-like porous structure and a Sulzer SMX (TM) static mixing element. Refractive index matching between two immiscible fluids and the internal structures enables optical measurements to be performed. The droplet size and position within the internal structures were observed by laser-induced fluorescence. The results show that at low flowrates, droplets follow preferred paths, whereas at higher flowrates, they are more homogeneously distributed within the structures. The droplet size distribution was found to be well represented by the Sauter mean diameter. Measuring along the axis of the two static mixers, we found that droplets disintegrate more quickly in the foam-like porous structure. As both geometries have the same porosity and hydraulic diameter, we conclude that the change in the free cross section is also an important parameter. We observed that in the geometry with large changes in the free cross section, the droplets are smaller. (C) 2016 Published by Elsevier Ltd.