An analytical method for determining nitroaromatic explosives in vapour phases is presented. Samples were collected by pumping air through glass fibre filters and polyurethane foam adsorbents, and an on-line extraction system combining supercritical fluid extraction (SFE) and high-performance liquid chromatography (HPLC) was developed. This allows analytes to be transferred from the adsorbent to the HPLC system via a porous graphitic carbon trap. When using gradient elution with a suitable mobile phase, most of the nitroaromatic isomers tested were separated. The proposed method is fully automated, allows a complete analysis to be processed in less than 30 min, and it is compatible with most of the organic solvents commonly used as SFE modifiers or additives. The method has been applied to the analysis of real samples obtained from headspace sampling of military-grade 2,4,6-trinitrotoluene and has been shown to constitute a promising alternative for assessing whether areas are mined in landmine-clearing operations.