Gd2O3:Eu scintillators with nano-crystalline structures were successfully synthesized through a hydrothermal process and subsequent calcination treatment as a converter for X-ray imaging detectors. In this work, Eu-doped Gd2O3 nano-crystalline powders as a function of calcination temperatures and times were prepared by a hydrothermal process and subsequent calcination in the electrical furnace. Scintillation properties such as luminescent spectra, light intensity and decay time were measured by changing the temperatures and times in heat-treatment of as-synthesized nanocrystalline powders. The synthesized samples with different morphology such as nano rods and particles due to calcination temperature were observed. The sample prepared at 1100Â°C calcination temperature and 5 hour showed the highest light intensity by X-ray excitation. And the scintillator emitted a strong red light at near 611nm under photo-and X-ray luminescence for its potential X-ray imaging detector applications.