The purpose of this study is to investigate the effects of mixing three kinds of zeolites (MFI, MOR, and BEA) with the dimethyl ether steam reforming(DME-SR) Cu/gamma-Al2O3 catalyst to improve H-2 yield at low temperatures, and to identify the de-NOx performance of a combined system of SR catalyst and Lean NOx Trap(LNT). The SR catalyst was prepared by the impregnation method, and a commercialized LNT catalyst was used. The SR reaction experiment was conducted to investigate the effect of the coexistence of CO2, O-2, NO, and NO2 among the exhaust gases of the DME engine on the H2 yield. The study found that the proper mixing of Cu/gamma-Al2O3 and zeolite increased the H2 yield at low temperature improving DME hydrolysis. The variation in the H-2 yield according to the kinds of zeolite in the SR catalyst was due to the characteristics of zeolite. The Cu/gamma-Al2O3 catalyst mixed with 10% MOR showed the highest H-2 yield. A combined system of SR and LNT uses the H-2 generated mainly from the Cu-based catalyst using the DME-SR reaction for the LNT. When H-2 generated from the SR (Cu/gamma-Al2O3 + MOR10) catalyst was used as the reductant of LNT, the NOx conversion at 350 degrees C or below was improved up to 15% compared to when DME was used. This demonstrates that H-2 as the reductant of LNT is more beneficial than DME. The H-2 generated from the SR catalyst can be used as the reductant of LNT in an after-treatment system. Meanwhile, the SR catalyst that was mixed with zeolite caused the carbon deposition, but the combined system of SR + LNT caused no carbon deposition because the carbon deposited on the SR catalyst reacted with O-2 during the lean-operating period. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.