The luminescent characteristics of new multicomponent oxide (Y2O3-GeO2):Mn thin films prepared by r.f. magnetron sputtering are described. High-luminance yellow emissions were obtained in photoluminescence (PL) and electroluminescence using (Y2O3-GeO2):Mn thin films prepared with a GeO2 content of 5-84 mol%. It was found that the GeO2 content dependence of luminance obtained in (Y2O3-Ge2O7):Mn thin-film electroluminescent (TFEL) devices was similar to that of PL intensity as well as the crystallinity of the thin-film emitting layers used in the devices. A luminance of 7700 cd/m(2) was obtained in 1-kHz-driven TFEL devices using (Y2O3-Ge2O7):Mn thin films prepared with a GeO2 content of 40 mol%.