In this study, we attempted to reduce firing voltage of AC-PDP by alloying MgO protective Layer with CaO. Also, spray coating of single crystal MgO powder has been used to improving Exo-electron emission characteristics and reducing the statistical discharge delay in plasma displays. The properties of discharge depending upon the single crystal MgO powder are investigated. Plasma display having powder coated MgCaO Protective Layer shows lower driving voltage and higher efficacy than of uncoated, conventional panel.