For decades, hexavalent chromium has been used in the surface treatment of aluminum alloys in the aerospace industry. In the sealing process of anodic coatings, hexavalent chromium provides surface protection with excellent corrosion resistance. However, the toxicity and carcinogenity of chromium substances signify the need for more sustainable alternatives. Herein, the more environmentally friendly rare earth metal cerium is investigated as potential candidate to replace chromium to seal the pores of anodized Al alloy 2024-T3 sample surfaces. Sealing was performed in cerium chloride solution with the addition of hydrogen peroxide as accelerant to form cerium oxide nanoparticles. Several sealing conditions were investigated: i) sealing immersion time, ii) ratio of CeCl3:H2O2, iii) CeCl3 concentration, iv) addition of surfactant, v) stirring conditions and vi) hydrothermal sealing. Results were evaluated using contact angle measurements (CAMs), scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM showed increased number and size of cerium oxide nanoparticle clusters as a function of immersion time under stirred conditions. CAM and XRD results indicated changes in surface characteristics with the addition of surfactants and altered CeCl3:H2O2 ratio. The findings in this thesis supports the earlier proposed theory that cerium could be used as an environmentally friendly alternative to hexavalent chromium. The thesis work clearly shows that it was possible to control some surface characteristics of the Al alloy samples, such as the number of cerium oxide nanoparticles and the morphology of nanoparticle clusters.