Fine particles of ZnO- and CaO-doped CeO2 for use as an ultraviolet (UV) filter were synthesized via soft solution chemical processes at 40 degreesC and final pH 5-6. Especially, Ce1 - xZnxO2 - x solid solutions were systematically investigated in a wide ZnO concentration range for the first time and the solubility limit of ZnO in a fluorite structure was suggested to be x = 0.561. Minor CaO solubility in ceria was observed under present reaction conditions (pH 5 - 6). Novel nanoparticles with significantly reduced oxidation catalytic activity, as well as excellent UV-absorption capability were obtained by doping ZnO or CaO in CeO2.