Abstract: An aqueous dispersion having a pH value of between 3 and 7 containing 1 to 35 wt. % of a pyrogenically produced silicon-aluminium mixed oxide powder with a specific surface area of 5 to 400 m2/g, wherein the proportion of aluminium oxide in the powder is between 90 and 99.9 wt. % or between 0.01 and 10 wt. %, the surface of the powder comprises zones of aluminium oxide and silicon dioxide and the powder exhibits no signals for crystalline silicon dioxide in an X-ray diffractogram. Said dispersion may be used for the chemical-mechanical polishing of conductive, metallic films.