Effects of dopant in BaMnO3 perovskite oxide on the NO direct decomposition activity were investigated. NO direct decomposition activity was greatly elevated by doping La and Mg for Ba and Mn site in BaMnO3, respectively. The highest N-2 yield was achieved on Ba0.8La0.2Mn0.8Mg0.2O3. The NO decomposition rate increased with increasing NO partial pressure with P-NO(1.19). Coexistence of oxygen lowered the N-2 yield with P-O2(-0.18); however, N-2 yield of 40% was sustained even under coexisting of 5% O-2 at 1123 K. Adsorption state of oxygen was also studied with temperature programmed desorption (TPD) method and the desorption temperature of oxygen was lowered by doping Mg for Mn site in BaMnO3. (C) 2007 Elsevier B.V. All rights reserved.