Zirconia-based oxide sorbents for NOx has been investigated to clarify the role of additives. Addition of yttria to Mn-Zr oxide improved the sorption capacity due to enhanced basicity and larger surface area. A small amount of transition metal oxide as additives was effective in promoting the sorption-desorption capability. A small addition of Mn or Co to ZrO2 was effective in achieving reversible sorption and desorption of NOx due to their activity as a reduction-oxidation catalyst. These oxides were active for the oxidation of NO to nitrate ions via NO2 in an oxidizing atmosphere and reduction of nitrate ions in the presence of a gaseous reductant. The NOx sorptive capacities of Mn-containing sorbents were significantly deteriorated in dilute SO2. The NOx sorption capacity of 0.5 wt.% Co/ZrO2 was lowered only slightly in the initial stage of NO2 sorption with dilute SO2.