Protein ingredients are generally considered bland in flavor. However, during storage, various chemical processes may occur, such as oxidation of residual lipids and amino acids, degradation of amino acids, and the Maillard reaction between proteins and reducing sugars. These reactions can significantly alter the volatile profile of plant-based foods by generating desirable or undesirable odors. To better understand the flavor chemistry of plant proteins and identify the key aroma-active compounds and their formation pathways, it is necessary to analyze their volatile profile using advanced analytical techniques. One such method is the combination of headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry-olfactometry (GC-MS-O). This technique offers a rapid, non-invasive way to extract and detect volatile compounds and key odorants from complex proteinaceous foods. This chapter describes detailed protocols for the analysis of volatile compounds in plant proteins through HS-SPME GC-MS-O.