2,3,4-Triphenylquinoline (tpq) ligand and its Ir(III) complex Ir(tpq)(2)(acac) were prepared and their photonic properties were investigated as red electrophosphorescent material. The photo luminescence (PL) spectra of tpq and Ir(tpq)(2)(acac) in dichloromethane showed a peak at 450 mri and 607 nm, respectively, at room temperature. The small Stokes shift between the 3 MLCT absorption and emission bands shows that Ir(tpq)(2)(acac) emits from a predominantly 3 MLCT excited state. The theoretical calculation of the Ir(III) complex was performed by an ab initio method, and the result calculated by time dependent density functional theory (TD-DFT) showed that the Ir(III) complex underwent a strong 3 MLCT transition because of the strong coupling between the 5d-orbital of It atom and the highest occupied molecular orbital (HOMO) of tpq ligand. Thus, it is concluded that this complex is a good candidate for a highly efficient electrophosphorescent material. (C) 2006 Published by Elsevier B.V.