The reaction between hydrogen and NO was studied over 1 wt.% Pd supported on NOx-sorbing material, MnOx-CeO2, at low temperatures. The result of pulse mode reactions suggest that NOx adsorbed as nitrate and/or nitrite on MnOx,-CeO2 was reduced by hydrogen, which was spilt-over from Pd catalyst. The NO,. storage and reduction (NSR) cycles were carried out over Pd/MnOx-CeO2 in a conventional flow reactor at 150 degreesC. In a storage step, NO was removed by the oxidative adsorption from a stream of 0.04-0.08% NO, 5-10% O-2, and He balance. This was followed by a reducing step, where a stream of 1% H-2/He was supplied to ensure the conversion of nitrate/nitrite to N-2 and thus restore the adsorbability. It was revealed that the NSR cycle is much more suitable for the H-2-deNO(x), process in excess O-2, compared to a conventional steady state reaction mode. (C) 2003 Elsevier B.V. All rights reserved.