The present work aims to evaluate mordenite as a support in Pd catalysts for the decomposition reaction of NO. In this way, two synthetic methods were used for mordenite preparation and compared with commercial mordenite (CBV10A). The mordenites were synthesized by two procedures: (1) employing sodium aluminate and Aerosil siliceous (Degussa) and (2) employing natural clay as an alternative source of Al and Si. The prepared materials showed specific superficial areas in the range of 300-360 m(2) g(-1) and high crystallinity. The materials presented similar conversions for NO decomposition, suggesting that the different methods of preparing mordenite did not interfere in the catalytic activities of the palladium catalysts. Furthermore, the results of N2O formation gave the following selectivity order: MOR-CBV10A > MOR-ARG > MOR-IZA. (C) 2007 Elsevier B.V. All rights reserved.