A plasma-catalyst reactor was used to eliminate a low concentration (180ppm) of 2-heptanone in air by total oxidation. This VOC is representative of a class of odorous ketones. A DBD-type plasma was generated through a platinum-based catalyst supported on an alumina wash-coated honeycomb monolith by means of a high voltage bi-polar pulsed excitation. The 2-heptanone elimination efficiency increases with the energy density. More than 97% of 2-heptanone conversion is observed, in dry air condition for an energy density of 200 J/L. An important synergy effect has been observed between cold plasma and catalyst, the 2-heptanone conversion remaining less than 50% on an uncoated monolith, even at an energy density value higher than 500 J/L. The presence of water (3 mol%) in the gas phase, slightly decreases the efficiency of the 2-heptanone elimination, but strongly decreases the ozone formation in the 100-300 J/L energy density range. (C) 2003 Elsevier B.V. All rights reserved.