NOx adsorption/desorption capacities of barium aluminates were measured under representative exhaust gas mixture at temperatures below 550 degrees C. The solid doped with Pt or not, exhibits good NO2 sorption capacities with a reversible adsorption to desorption process. With bulk BaO, desorption was observed at high temperature. The different behaviour between the two catalysts is explained by the fact that strongly bonded carbonates are formed on bulk BaO while they do not exist on barium aluminate, therefore allowing the formation of nitrates which can be decomposed by a thermal process. SO2 poisoning was also studied.