Spatial-and time-resolved temperature distributions over a Pt/Ba/Al 2 O 3 model NO X storage/reduction (NSR) catalyst were measured using infra-red thermography. The heat generated during regeneration was correlated to surface nitrate reduction, thereby revealing the concentration of surface nitrates at specific locations along the catalyst. The results demonstrate that there is more nitrate formation at upstream positions relative to downstream, or from front to back of the catalyst, with short trapping times. However, as more NO X was trapped on the catalyst during longer trapping times, it was found that the largest amount of NO X was trapped slightly downstream of the inlet, evolving to a local maximum in amount trapped. Applying infrared (IR) thermography to this system resulted in a spatially resolved calorimetry method via the correlation of temperature to the distribution of sorbed nitrate species along the catalyst.