The present invention relates to a catalyst, in particular for the preparation of phthalic anhydride by gas phase oxidation of o-xylene and/or naphthalene, having an inert support and at least one layer which has been applied thereto and has a catalytically active composition comprising TiO2, characterized in that at least a portion of the TiO2 used has the following properties: (a) the BET surface area is more than 15 m2/g, (b) at least 25% of the total pore volume is formed by pores having a radius between 60 and 400 nm, and (c) the primary crystal size is more than 22 ångstrøm. Also described is a preferred process for preparing such a catalyst, and the preferred use of the titanium dioxide used in accordance with the invention.