Guayule (Parthenium argentatum), a shrub native to the arid region of the U.S. southwest and Mexico belonging to the Asteraceae family, is a source of high quality, hypoallergenic natural rubber with applications in pharmaceutical, tire, and food industries. Production of rubber results in a substantial amount of resin-containing residues which contain a wide variety of secondary metabolites (sesquiterpene esters, triter-pene alcohols, fatty acids, etc.). In order to enhance the eco-nomic viability of guayule as an industrial crop, value-added use of the residues is needed and has the potential to re-duce gross rubber production costs. The main objective of this research is the characterization of guayule resin using rapid and accurate analytical techniques to identify com-pounds of potential commercial value. Guayule resin is in-herently complex and includes many high-molecular-weight and non-volatile compounds that are not easy to observe using traditional chromatographic techniques. The combina-tion of two mass spectroscopy techniques: gas chromatogra-phy mass spectroscopy (GC-MS) and high-resolution Fourier transform ion cyclotron resonance mass spectroscopy (FT-ICR MS), were used to characterize the composition of the ex- tracted resin from guayule (Parthenium argentatum). FT-ICR MS was used to characterize hundreds of compounds with over a wide range of molecular weights and degrees of aro-maticity at higher levels of mass accuracy than other forms of mass spectrometry. GC-MS was used to identify volatile compounds like mono-and sesquiterpene compounds. (C) 2020 The Author(s). Published by Elsevier Inc.