Y2O3 materials are considered as a promising optical material because of their high melting point, broad range of transparency (0.2-8 um), and high corrosion resistance. Therefore, Y2O3 ceramics have been developed for laser host materials, infrared-domes, nozzles, refractories and components of semiconductor devices. Conventionally, producing transparent Y2O3 ceramics requires severe sintering condition to get nearly full density. To achieve high density, it needs techniques such as special furnaces, sintering additives and powder synthesis. Most of all, powder synthesis is crucial because of its significant effect on the sintering behavior. It is well known that, the use of ultrafine, monosized and low-agglomerated powders is essential to the fabrication of transparent yttria ceramics. In this study, we prepared monosized spherical Y2O3 powder by homogeneous precipitation which is based on the thermal decomposition of urea. The effect of yttrium concentration, reaction time and calcination temperature on morphology, size, distribution and agglomeration of the powders were investigated. In addition, sintering behavior of the spherical powders and factors affecting transparency were also discussed.