Two kinds of zirconia-containing mixed oxide gels (zirconia-silica and zirconia-magnesia) were synthesized as rigid microparticulates by means of the sol-gel process. The physical and chemical characteristics, such as the particle-size distribution, the specific surface area, the crystal structures and the acid-base properties of the oxides, were examined. The molar ratio of Si/Zr and Mg/Zr on the surface of the two mixed oxides was estimated, respectively, by means of electron spectroscopy. The chromatographic performance of zirconia-silica and zirconia-magnesia was compared to that of silica and zirconia with pyridine and phenol as solutes. The separations of nitroanilines and toluidines were achieved on the two mixed oxides under normal-phase liquid chromatographic conditions, respectively.