Cold-start emissions significantly contribute to total vehicular pollutant emission profiles. There has therefore been a significant amount of research focused on catalytic aftertreatment systems that can mitigate CO, hydrocarbon and NOx emissions at low temperatures. Recently, passive NOx adsorbers (PNAs) have been developed, and these can store or trap NOx at low temperature and are designed to release the trapped NOx at higher temperature ranges, where downstream NOx reduction catalysts are active. Pd/BEA is reported to be one such PNA. In this study its NOx storage at low temperatures and release at higher temperatures was characterized using temperature programmed (TP) experiments and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The influence of CO was investigated and was shown to improve the amount stored at low temperature and also induce higher temperature desorption, in a range that is applicable for downstream NOx reduction. Without the reductant, NOx release primarily occurred at temperatures too low to be practically relevant. [GRAPHICS] .