The invention relates to a process for preparing an essentially spherical support for olefin polymerization catalysts, which comprises the steps: preparation of a hydrogel comprising a cogel of silicon oxide and at least one further metal oxide, if appropriate, washing of the hydrogel until the content of alkali metal ions is less than 0.1% by weight, based on the weight of solids, extraction of the water from the hydrogel until the water content is less than 5% by weight, based on the total content of liquid, and drying of the hydrogel to form a xerogel. According to the invention, the extraction step comprises at least one first extraction with a first organic solvent which is at least partially miscible with water down to a water content of 50% by weight, followed by at least one second extraction with a second organic solvent which is at least partially miscible with water.