In this paper, we report the results of the examination of various rare earth oxides for future CMOS gate insulator applications. The electrical and physical characteristics of various rare earth metal oxides have been investigated. Most of the rare earth metal oxides showed excellent electrical properties and smooth surface especially, La2O3. Other materials such as Dy2O3 and Lu2O3 showed good electrical characteristics in terms of frequency dependence, however, it was found that it is necessary to obtain the optimum process conditions (deposition temperature, RTA temperature, RTA ambient etc.) for each rare earth oxide material.