In recent years, chemical microprocesses have attracted significant interest of both chemical process industry and research community. These processes occur in equipment with characteristic dimensions at micrometer and sub-millimeter scale. An important class of microdevices is represented by falling-film microcontactors with interfacial areas higher than 10 000 m2m(-3). For a numerical investigation of the transport processes in such microdevices, a rigorous mathematical model is developed enabling a detailed description of the process performance. The model yields far more reliable results than common simplified modeling methods.