Three different techniques have been considered to prepare ceria nanoparticels with and without Tween 80 as a surfactant.Phase formation and crystal structure were examined by X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM). The particle sizes of the three prepared samples are 15nm, 5nm and 4nm. The measurements clarified the role of each of Tween 80 as a surfactant and the nanoparticle size on the values of zeta potential (ζ).The maximum zeta potential of un-surfactant nano-ceria in water medium was obtained at pH=5, accordingly, a neutral colloidal solution with small particle size without surfactant is suitable for medical applications. On the other hand, the results clarify that, UV absorbance depending on the refractive index of the dispersion medium and increases with decreasing the particle size for surfactant samples. These are interesting applicable results as a good coating, where the dispersed of small amount of nano-ceria in neutral water medium used to prevent UV hazards for essential fields such as furniture and medical bottles.