Abstract: The invention relates to a silver-comprising catalyst system for the preparation of aldehydes and/or ketones by oxidative dehydrogenation of alcohols, in particular the oxidative dehydrogenation of methanol to form formaldehyde, comprising a first catalyst layer and a second catalyst layer, wherein the first catalyst layer consists of a silver-comprising material in the form of balls of wire, gauzes or knitteds having a weight per unit area of from 0.3 to 10 kg/m2 and a wire diameter of from 30 to 200 ?m and the second catalyst layer consists of a silver-comprising material in the form of granular material having an average particle size of from 0.5 to 5 mm and the two catalyst layers are in direct contact with one another. The invention further relates to a corresponding process for the preparation of aldehydes and/or ketones, in particular of formaldehyde, by oxidative dehydrogenation of corresponding alcohols over a silver-comprising catalyst system.