The organic impurities, such as CxHy, on the MgO surface are known to be an important parameter that affects the panel-aging characteristics in an ac plasma display panel (PDP). Accordingly, the RF-plasma pretreatment on the MgO layer is adopted to reduce the panel-aging process time by reducing the organic impurities. The resultant changes in the discharge characteristics during the panel-aging process, including the firing voltage, formative address delay time, statistical address delay time, and wall voltage variation, were examined in comparison with both cases with and without plasma pretreatment on MgO layer using various gases in the 50-in. full-high definition ac-PDP with He (35%) - Xe (11%) contents. It is concluded that the Ar or Ar followed by O-2 plasma pretreatment was the most effective in eliminating the residual impurities on the MgO surface, thereby reducing the panel-aging process time.