The performance of a.c. plasma display panels (PDP) is influenced strongly by the surface glow-discharge characteristics on the MgO-thin films. This paper deals with the surface glow-discharge characteristics and some physical properties of MgO-thin films prepared by reactive RF planar unbalanced magnetron sputtering in connection with a.c. PDP. The samples prepared with the d.c. bias voltage of -10 V showed lower discharge voltage, lower erosion rate by ion bombardment, higher optical transparency and higher crack resistance in the annealing process than those samples prepared by conventional magnetron sputtering or E-beam evaporation.