In order to improve both the operating voltage and the luminous efficiency of the protective layer for AC Plasma Display Panels, controlled amount of TiO2 was added to the pure MgO. The effect of the TiO2 addition on both the electrical properties (firing voltage & sustain voltage) and the luminous efficiency of the Mg2−2xTixO2 films deposited by e-beam evaporation was investigated. By addition of a proper amount of TiO2 to MgO, the dielectric constant of protective layer was increased to the 11, which has higher than that of bulk MgO. When the composition of Ti in the thin films was about 2.45at%, firing and sustain voltages were very low. With this composition, the luminous efficiency characteristics were much better than that of any other protective layer. When compared to that of the conventional MgO protective layer, the luminous efficiency showed an increase by 28%.