La2-xBaxNiO4 (x <= 1.2) catalysts have been prepared by citrate method. XRD patterns and IR spectra indicate that with the doping of Ba, more BaCO3 appears and perovskite-like structure is seriously distorted. In directly decomposing 4% NO, the highest N-2 yield is achieved with La1.2Ba0.8NiO4 composed of perovskite-like structure phase and BaCO3 in the absence/presence of oxygen. The results of iodometry, and H-2-TPR reveal that the increase in Ba causes the increase in Ni(3+)content. O-2-TPD and NO adsorption tests confirm that Ba doping resulted in the increase in oxygen vacancy (Vo). Thus, the redox capability and the amount of Vo are enhanced. It is suggested that the BaCO3 phase, NO,, storage component, contributes to the increase in activity by NO-TPD, NO2-TPD and in situ DRIFT. Thus, BaCO3 plays an important role in quickening LIP the run of catalytic NO decomposition recycle. (C) 2008 Elsevier B.V. All rights reserved.