A study was performed to examine the aging behaviors of Al-2.1Li-2.9Cu alloy by differential scanning calorimetry and transmission electron microscopy. DSC measurements were conducted over the temperature range of 25∼550℃ at a heating rate of 5℃/min. for the specimens aged at 130, 160, 190℃ and 220℃ for various times after solution treatment at 540℃ for 30 minutes. The peaks due to the formation of G.P.zone were not detected in the specimens aged at 130 and 160℃, but those at 190 and 220℃ appeared in DSC curves. The heat absorption due to the dissolution of δ` phase was increased with increasing aging time at 130℃ aging. In contrast, those values for the specimens aged at 160 and 190℃ were initially increased and inversely decreased at the transition time of 72 and 1 hour, respectively. The heat evolution due to the formation of T₁phase was nearly unchanged at 130℃ aging, but at 160℃ and 190℃ aging, drastically decreased after the transition time. It can be considered that the increase of T₁phase results in the decrease of δ` phase when aging time is longer than the transition time. The hardness of the specimen aged at 190℃ is initially higher compared with that at 160℃, however, the peak hardness shows the lower value than that at 160℃.