The objective of this work was to investigate NO, removal with a hybrid system consisting of a de corona discharge and a catalyst at a room temperature (22 degreesC) in the presence of ammonia. The experimental procedure was as follows. A positive dc corona discharge was generated between a stainless steel hollow needle and a flat mesh made of brass. The needle was placed perpendicularly to the mesh maintaining the interelectrode distance of 40 mm. The outer and inner diameters of the hollow needle were 2 and 1.6 mm, respectively. The catalyst used in this investigation was a layer Of V2O5 and TiO2 deposited on Al2O3 globules of 5-6 mm in diameter. They were placed on the mesh so that the distance between the tube and the globules was 30 min. The catalyst was either saturated with NH3 or free of NH3. A gas mixture of N-2 (80%):O-2 (5%):CO2 (15%):NO (200 ppm) flowed through the tube with a flow rate of 11/min. Ammonia was added to the gas mixture through a hollow needle in a concentration of either 400 ppm when NH3-free catalyst was used or 30 ppm when catalyst saturated with NH3 was used. Results of the investigation showed that the hybrid system (with NH3-saturated catalyst) removes up to 96% of NOx with an energy efficiency of 3.4 g NO/kWh. Without the catalyst, NOx removal in the "pure" corona discharge in the gas mixture with ammonia was lower (up to 66%). Also the energy efficiency was lower (about 1.8 g NO/kWh). The obtained results showed that the investigated corona discharge-catalyst hybrid system is attractive for NO., removal because of relatively high efficiency both in NO, decomposition and energy consumption. (C) 2003 Elsevier B.V. All rights reserved.