Abstract: The invention relates to a process for the oxidation of unsaturated hydrocarbons, wherein an unsaturated hydrocarbon, an oxygen-containing oxidizing agent, a palladium complex as the catalyst containing a ligand of the formula (I) wherein R is a saturated, halogenated alkyl radical having from about 1 to about 20 carbon atoms, and optionally auxiliary substances in a liquid phase based on (?1) from about 10 to about 100 wt. % of a protic polar solvent and (?2) from 0 to about 90 wt. % of an aprotic polar solvent, the sum of components (?1) and (?2) being about 100 wt. %, at a temperature in a range from about 30 to about 300° C. under a pressure in a range from about 1 to about 200 bar, such that a liquid phase containing oxygen-containing hydrocarbons is obtained.