Thermodenuders are used to remove the volatile fraction of an aerosol. All designs until now have a cooled adsorption section where the volatile material is trapped, but theoretical considerations suggest that the adsorption section should be heated. Therefore, we built a thermodenuder with a heated adsorption section. We tested its performance with respect to particle penetration and its ability to remove DEHS coated onto NaCl nuclei. The measured losses are lower than in previously published designs and the DEHS removal appears to be satisfactory. Additionally, the new thermodenuder is practical for field use thanks to its small size. It should therefore be a good alternative to previous designs. (C) 2007 Elsevier Ltd. All rights reserved.