ZnGa2O4 and Zn1-xMnxGa2O4 were investigated as potential low voltage cathodoluminescence phosphors for use in vacuum fluorescent displays. A low-voltage cathodoluminescence spectrophotometer was developed for phosphor characterization. Brightness was measured as a function of anode voltage (10 to 300 V). The effects of activator concentration, phosphor layer thickness, deposition process, and internal pressure were examined. The stability of these oxide phosphors in high vacuum and absence of corrosive gas emission under electron bombardment, offer advantages over commonly used sulfide phosphors.