We have investigated the effect of electrical aging to improve emission reliability of carbon nanotube (CNT) emitter. The CNT emitters were prepared by the screen-printing of the CNT paste. The electrical aging treatment was carried out in a high vacuum chamber by applying the pulsed dc voltage. The field emission measurements and lifetime tests were performed on the CNT emitters depending on the electrical aging time and current density. After the electrical aging treatment, emission properties of CNT emitter were suppressed but the half lifetime was dramatically improved. (c) 2007 Elsevier B.V. All rights reserved.