This paper reports on the change in the surface condi-tion of the MgO thin film in an ac plasma display panel during thedischarge aging process. The superficial layer on the MgO thin filmwas created during the discharge aging process, which was relatedto the minimum sustain voltage and the light intensity emitted fromthe Neon+Xenon gas mixture discharge. The superficial layer onthe MgO thin film was observed using a transmission electron mi-croscope. The X-ray diffractometer pattern of the MgO thin filmafter the discharge aging process was different from the pattern atthe beginning of the discharge aging process