A new compound, 2,2'-dimethyl-3,3',5,5'-tetrakis(p-tolyidiamino)biphenyl (DTTAB), was synthesized and investigated as a hole-transporting material for organic light-emitting diodes. The luminous efficiency of electroluminescent device was improved by using DTTAB instead of NPB at lower driving voltage, Suggesting that the DTTAB layer can efficiently accept holes from the hole-injecting layer and transport holes into an adjacent emitting layer.