Plant-emitted volatile organic compounds (VOCs) play a significant role in signaling and tolerance to biotic stressors, including insect pest infestation. Mycorrhizae, a symbiotic fungus, improves the tolerance of blackgram plants to Spodoptera litura by altering the profiling of foliage VOCs. Recently, gas chromatography-mass spectrometry (GC-MS) coupled with headspace (HS) trapping of VOCs is the most frequently used analytical technique to understand the metabolic process and responses of plants to biotic stresses. This method performs four steps such as (i) trapping of HS-VOCs, (ii) concentration and enrichment of VOCs, (iii) transfer of VOCs from air sample to analytical device, and (iv) detection and identification of compounds. HS volatiles is trapped using fiber polymers like Tenax TA and desorbed thermally in GC-MS with TD autosampler and thermal desorption (TD). The identification of VOCs compounds is performed by searching mass spectral peaks against NIST mass spectral library. This chapter provides the detailed procedure for the estimation of plant-produced VOCs using HS sapling coupled with gas chromatography-mass spectrometry (TD–GC/MS) with TD autosampler and thermal desorption method.