The essential oil of key lime (Citrus aurantifolia) was obtained by steam distillation at normal conditions (1.0 bar/25°C) with steam at 110°C, during 10h. The GC analysis identified about 10 main substances, being limonene, p-cymene, myrcene and β-bisabolene the most significant compounds. Aldehyde content increased significantly during distillation time (upper phase). After 10h of process, oil has presented more than 3% of aldehydes content due to oxidative reactions.