Novel red-emitting electrophosphorescent devices were fabricated by doping an Ir complex, Ir(tpq)(2)(acac), based on 2,3,4-triphenylquinoline (tpq) ligand. The EL spectrum of the device showed emission maximum peak at 611 nm and CIE coordinates of that were (0.664, 0.332) at 12V, respectively, due to long conjugation length of Ir(tpq)(2)(acac). The luminance of the device with Ir(tpq)(2)(acac) was 4160 cd/m(2) at 14V. The maximum luminous efficiencies and power efficiency of the device with Ir(tpq)(2)(acac) were 3.14 cd/A (8.01 mA/cm(2)) and 1.82 lm/W (0.24 mA/cm(2)). More characteristics and charge transport mechanism will be discussed.