The actual coupling is then achieved through a mass flux boundary condition at the electrochemical interface which establishes an interdependence between the two processes. Solving the resulting multi-scale problem thus always requires that near-surface fluxes and concentrations are aligned between the kinetic and transport models. Depending upon how these two models are set up and combined in practice, however, we distinguish two basic modeling approaches in the current literature. The approaches generally differ in their primary focus and, hence, the level of theory used for the individual model components, as illustrated in Figure . The first approach uses phenomenological kinetics to approximate the partial current density J surf that is generated through the surface reaction and fed as input into a (usually) rather elaborate transport model. As a result, this approach often addresses more complex transport phenomena and mechanisms (diffusion, migration, convection) or design strategies at the device level through, e.g., simulations of realistic porous electrode morphologies, gas diffusion electrodes (GDEs), and even full electrolyzers (including cathode/anode and membrane) . Alternatively, the second approach is to put the stronger focus on the surface kinetics and couple to transport through a predictive-quality J surf that is computed from a first-principles based microkinetic model (1p-mkm). This approach will thus directly include the free energy profile of elementary surface reaction steps while integrating microscopic details of an assumed catalytic mechanism. At this point, it should be em-phasized that the above classification simply reflects our view of the prevailing status quo and that there is, in principle, no conceptual limitation to, e.g., coupling a 1p-mkm to a most elaborate mass transport model. This situation is analogous to that observed in the field of thermal heterogeneous catalysis. This short review aims to give a current overview over corresponding transportcoupled kinetic models for heterogeneous electrocatalysis. We first separately discuss the two aforementioned modeling approaches, distinguished by whether the surface reaction is included via a phenomenological or first-principles based kinetic model.