In the present report, bio-reduction of cerium nitrate into cerium oxide nanoparticles has been done using aloevera leaf extract. The synthesized CeO2 nanoparticles were characterized by PXRD, FTIR, UV-DRS, FESEM, EDAX and PL. From the PXRD analysis, it is found that the synthesized CeO2 nanoparticles were the face centered cubic structure. The crystalline size is found to be about 7 nm and 12 nm for the CeO2 nanoparticles before and after calcination respectively. FTIR spectra exhibit the formation of CeO2 nanoparticles. The UV – Vis spectra shows an absorption peak at 320 nm. The FESEM analysis, showed spherical shaped CeO2 nanoparticles and its size is about 50 nm.