The abatement of NH3 from waste streams has become an important environmental issue. Selective catalytic oxidation (SCO) of NH3 to N-2 has emerged as a potential technology for taking care of NH3 slips and NH3 in waste streams. In this work, we describe the catalytic activity of Fe-zeolite catalysts prepared by incipient wetness technique, ion exchange and hydrothermal synthesis in the SCO of NH3 to N-2 using a fixed bed flow reactor. Selective catalytic oxidation was carried out at 573-723 K and 10(5) Pa with gas hourly space velocities (GHSV) between 24 000 and 240 000 h(-1). Results obtained showed that Fe-ZSM-5 catalysts prepared by incipient wetness technique were active for NH3 conversion (77-100%) and selectivity to N-2 (65-100%). Fe-ASA and Fe-Beta showed good catalytic activity and selectivity, but their activity and selectivity were less than that of Fe-ZSM-5. The effects of water vapour, Fe loading, and activation method on the performance of these catalysts was also investigated. (c) 2004 Elsevier B.V. All rights reserved.