Nowadays, the Three-Way Catalyst (TWC) is the standard solution employed in the spark ignition (SI) internal combustion engines (ICEs) to reduce CO, HC, and NOx tailpipe emissions from vehicles, particularly those powered by gasoline. As regulations become more stringent and testing procedures more rigorous, the design of modern propulsion and after-treatment systems is evolving into complexity and as a consequence, the relevance of simulating the future behavior of a device is turning crucial. Therefore, it is necessary to develop numerical models embedding properly defined kinetic schemes, that can predict, robustly and accurately, the catalyst performances under various operating conditions. Compared to extensive experimental campaigns, these models are essential for reducing time and costs associated with the entire development process, from the concept phase to the calibration of the control system.