A novel organic electroluminescent device with EuGd complex (Eu 0.1 Gd 0.9 )(TTA) 3(TPPO) 2 as an emitter was developed. The characteristics of this device were described and both fluorescence and phosphorescence were observed. This phenomenon is discussed in terms of yields of phosphorescence from the triplet excited state of the Gd and Eu chelates because of the paramagnetic Gd 3+ ion strong perturbance to the spin orbit levels of the complex. Both the photoluminescent and electroluminescent efficiencies at different temperature from 77 K to 300 K were measured by integrating sphere technique. The results imply that the phosphorescent emission from the triplets excited state might be a new way to increase the theoretical efficiency limit in electroluminescent devices.