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