a process for preparing a bicyclooctanone , in particular 1 , 5 - dialkylbicyclooctan - 8 - one , by reacting a bicyclooctanol , in particular dialkylbicyclooctan - 8 - ol , with a . a catalyst applied to an active - carbon support and comprising heteropolyoxometallate anions of vanadium , molybdenum and phosphorus , and also a corresponding alkali - metal , alkaline - earth - metal and / or ammonium counter ion , and b . a gaseous , oxygen - containing oxidizing agent .