In this paper, a comparative study on the NO, reduction/regeneration capabilities at 300 degrees C of a Pt-Ba/gamma-Al2O3 catalyst is presented. Different reductants (H-2, CO, and C2H4) are used in the absence and presence of H2O in the rich phase. Lean/rich cycling experiments show that in the absence of H2O both H-2 and C2H4 are capable of reducing all the stored NOx, although C2H4 poisons the Pt sites by carbon decomposition. CO not only poisons the catalyst through carbon decomposition but also through formation of strongly bound isocyanates on barium sites. These isocyanates are removed by 02 in the lean phase. The type of reducing agent also affects the NO, storage route in the lean phase. H2O in the rich phase prevents poisoning of the catalyst by CO and C2H4, and all three reducing agents show comparable reduction efficiencies. (C) 2007 Elsevier B.V. All rights reserved.