The interest in applying plasma catalysis for various applications is significantly growing; therefore, a rapid discovery and optimization of catalysts in the plasma system is highly demanded. In this study, a new operando infrared (IR) thermography system was developed for high-throughput screening of the catalytic reactivity in ozone-assisted oxidation under realistic operating conditions. In the developed system, the gas flow was maintained under laminar conditions in a flow-through catalyst bed using a porous disc, and the enthalpy of the system was directly correlated with the catalyst activity. The performance of the developed system was confirmed for ozone decomposition and CO oxidation over different metal loaded-TiO₂ catalysts at wide operating parameters. Among four metals tested, Ag exhibited the highest activity for both ozone decomposition and CO oxidation, and its loading amount clearly corresponded with the CO oxidation rate and temperature increase measured by the operando IR thermography. Meanwhile, Mn had poor activity for CO oxidation, despite its high activity for ozone decomposition. Therefore, the operando IR thermography provided a rapid screening and deep understanding of catalysts for ozone-assisted oxidation. Unlike conventional point temperature measurements, IR thermography provides a two-dimensional temperature distribution in the catalyst, which can be sensitive in detecting undesirable “hot-spot” formation. Hence, the developed system can be used as a tool for reaction engineering and catalyst design and development.