Abstract: The cubic Y₂O₃:Eu red phosphors were prepared by hydrothermal method. The room temperature sharp characteristic emissions of Eu³⁺ ions were observed for the samples with different doped concentrations and pH values in reactive solution. The effect of the Eu³⁺ doping concentration on the fluorescence emission intensity was discussed. The optimum doped concentration for the luminescence intensity of Eu³⁺ is determined to be 9% for the cubic structure samples. The optimum pH value of reactive solution for obtaining the most intense emission is determined to be 6. In addition, the luminescence intensity of the Y₂O₃:Eu phosphors for hydrothermal method are comparative with that of commercial phosphor Y₂O₃:Eu. Therefore, it is a simple and easy method that Y₂O₃:Eu phosphors were prepared by hydrothermal method.