Limonene-O 2-N 2 and α-pinene-O 2-N 2 mixtures were oxidized in a jet-stirred reactor at atmospheric pressure, in the cool flame regime, and fuel-lean conditions. Samples of the reacting mixtures were collected, dissolved in acetonitrile, and analyzed by Orbitrap mass spectrometry after flow injection or chromatographic separation by ultra-high-performance liquid chromatography and +/-heated electrospray ionization and +/-atmospheric pressure chemical ionization. OH/OD exchange using D 2 O and reaction with 2,4-dinitrophenylhydrazine were carried out for probing the existence of hydroxy, hydroperoxy, and carbonyl functions in the products, respectively. A huge set of products of oxidation, including highly oxygenated organic products with five and more oxygen atoms, was observed. Aromatic and polyunsaturated products were detected. Van Krevelen plots, computed oxidation state of carbon and degree of unsaturation in products were used to rationalize the results.