Well dispersed ZrO2/SiO2 catalysts with a satisfactory thermal stability have been prepared by reaction between zirconium ethoxide dissolved in ethanol and hydroxyl groups of the silica support, followed by calcination in air at temperatures up to 700°C. Characterization of the catalysts in intermediate stages of the preparation by secondary-ion mass spectrometry (SIMS), infra-red spectroscopy (IR) and temperature-programmed oxidation (TPO) gives a detailed picture of the formation of the ZrO2 from the ethoxide precursor. Intensity ratios of the zirconium and silicon X-ray photoelectron spectroscopy (XPS) signals have been used to estimate the dispersion of the catalysts and to investigate their thermal stability. The results obtained on the ethoxide-derived catalysts are compared with those on ZrO2/SiO2 catalysts prepared by incipient wetness impregnation from an aqueous solution of zirconium nitrate. The work illustrates how useful the combination of XPS, SIMS, IR and TPO is for investigating the genesis of catalysts.