Process Intensification is the strategy of making significant reductions in the size of a chemical plant in order to achieve a given production objective. Innovations in catalytic reactors, which constitute the heart of such process technologies, are often the preferred starting point. Over the last two decades, innovative multifunctional reactor systems have been developed to intensify chemical processes by synergistically combining chemical reaction with momentum, heat and mass transport in a single vessel. This paper aims to emphasize an interdisciplinary approach to multifunctional reactor design. Examples from commercially practiced technologies are used to illustrate how process intensification can be achieved through multifunctional reactors. Furthermore, new developments in this area will be highlighted.