Terpenes are hydrocarbon compounds naturally found in plants. They already have a variety of uses, such as flavor and fragrance additives. Also, they can be blended with conventional or synthetic liquid fuels. Understanding the kinetics of terpenes combustion is important for the development of cleaner combustion, as well as for evaluating associated air pollution and environmental impacts. Therefore, the oxidation of terpenes has been performed under well control conditions. Limonene and α-pinene, two important terpenes, were oxidized in a jet-stirred reactor at 1 bar, in the cool flame regime, under fuel-lean conditions. Samples of the reacting mixtures were collected, dissolved in acetonitrile, and analyzed by high-resolution mass spectrometry. Direct flow injection or chromatographic separation by ultra-high-performance liquid chromatography. Heated electrospray ionization and atmospheric pressure chemical ionization were employed to characterize the products of oxidation. H/D exchange using D2O were performed for probing the presence of hydroxy and hydroperoxyl groups in the products. Reaction with 2,4-dinitrophenylhydrazine was used to assess the presence of carbonyl functions in the products. A large set of oxidation products, including highly oxygenated organic products with 5 and more oxygen atoms, was observed. Aromatic and/or polyunsaturated products were also detected. Van Krevelen plots, computed oxidation state of carbon, aromaticity index, and degree of unsaturation in products were used to analyze the results.