ABSTRACT: 2-Pentylfuran and isomers of 2-pentenylfuran are known to be mainly responsible for the undesirable reversion flavor of soybean oil. Solid-phase microextraction - gas chromatography - mass spectrometry was used to isolate, separate, and identify 2-pentylfuran and isomers of 2-pentenylfuran from soybean oil containing 5 ppm chlorophyll in a gas-tight sample bottle during oxidation under light. Both 2-pentylfuran and isomers of 2-pentenylfuran increase as light exposure time and added chlorophyll increased. The compounds were neither formed in the oil containing 5 ppm chlorophyll under dark nor in the chlorophyll-free soybean oil under light. The singlet oxygen oxidation mechanism for the formation of 2-pentylfuran from linoleic acid and isomers of 2-pentenylfuran from linolenic acid are proposed. Removal of chlorophyll will reduce reversion flavor formation.