@@ 1 Introduction Many recent studies have shown that ceria as addictive in the lean NOx trapping system [1] can improve the trapping capacity at low temperature. It is known that CeO2 can be as support for loading other storage materials such as Ba [2]. And it is documented that high BaO loading on CeO2 can stabilizes the adsorbed nitrites species significantly but decrease the amount of NOx storage [3]. Low amount of BaO (0.5, 1, 3 and 5 wt. ％) loaded on CeO2 is investigated to explore the modification of the trapping capacity and adsorbed species at low temperature (≤300 °C).