Nitrous oxide (N2O) is a greenhouse gas and damages the ozone layer. Nitrous oxide from nitric acid plants is currently the major industrial N2O source. Many catalysts are active for pure N2O decomposition, but few are effective under realistic conditions, due to the relatively low N2O concentration compared to those of inhibitors present in the exhaust gases, i.e. H2O, O-2 and NOx. In the present work, Si-SBA-15 and Al-SBA-15 were used to prepare Fe, Ru or Rh catalysts by ion-exchange, impregnation or precipitation method. The effect of steam treatment was also studied. Their activities were evaluated in an automated six-flow reactor system using a model tail-gas under conditions representative for nitric acid plants. The performance depends on the metal species and preparation method. When the carrier, preparation method and metal loading are the same, the activity decreases as follows: Rh > Ru > Fe. Steam-treatment has little influence on catalytic activity unlike for FeZSM-5 catalysts. Impregnated Rh on Al-Grafted SBA-15 catalyst shows the best performance per weight of catalyst. However, per mol of active metal (Rh, Ru and Fe) species, catalysts by ion exchange are better than those by impregnation. It is concluded that the improved performance of Rh on Al-grafted SBA-15 is caused by a better dispersion and an enhanced stability due to Al incorporation, but not due to an enhanced acidity thereof. (C) 2004 Elsevier B.V. All rights reserved.