The Photo-Fenton-Process utilizing the combinations Fe(II)/H2O2/UVA and Fe(III) oxalate/H2O2/UVA was employed with success to degrade biorefractory organic pollutants in landfill leachate. The rate of degradation of the organic pollutants depends on the concentrations of hydrogen peroxide and the iron catalyst, the pH value and the concentration of dissolved oxygen, A comparison of the Photo-Fenton-Process with the H2O2/Fe(IT) process and the H2O2/UVC process shows that the Photo-Fenton-Process gives a higher COD degradation and a reduced energy consumption of at least 30% compared to the H2O2/UVC process. By using photogenerated Fe(II) the amount of the iron catalyst required and the volume of sludge produced are strongly reduced.