The photoluminescence (PL) and cathodoluminescence (CL) characteristics of lithium gallate and lithium zinc gallate were investigated as a function of composition and firing temperature. As Li/Ga of Lithium gallate decreased, the emission peak shifted from about 420 to 390 nm under ultraviolet (UV) excitation. Similar results were obtained under cathode ray (CR) excitation. PL spectra of lithium gallates fired at high temperature were most similar to those of Li-deficient lithium gallate. This result clearly indicates that Lithium gallate fired at high temperature is Li deficient. The PL and CL emission spectra of Lithium zinc gallate consisted of a single broadband under UV and CR excitation. The emission peak of the composition of(1-x)Li0.5Ga2.5O4-xZnGa(2)O(4) shifted from 406 to 440 nm as x increased under UV excitation and the peak intensity decreased with x. However, the intensity increased with x under CR excitation. When the composition of lithium zinc gallate was 0.4Li(0.5)Ga(2.5)O(4)-0.6ZnGa(2)O(4), the brightest CL was observed.