Pickling hydroxide sludge (pickling sludge for short) generated in the stainless steel industry in Sweden is currently dumped in special landfill areas. After filtration the sludge contains 50-60 wt-% moisture. After drying at 120̊C it contains about 26 wt-% of metal oxides, such as Fe 2O3, NiO and Cr2O3 and 43 wt-% of CaF2. In order to facilitate the recycling of pickling sludge and/or to recover fluorine as an HF acid, different scale experimental studies to remove sulphur and/or fluorine directly from the sludge have been carried out. Theoretical thermodynamic calculation results show that the simultaneous removal of both sulphur and fluorine is possible when the temperature is above 1500°C under the oxidizing condition and in the presence of water vapour in the system. Experimental results show that the elimination degrees of sulphur and fluorine for pickling sludge can reach 99 wt-% and 84 wt-%, respectively. These results demonstrate that potentially feasible methods for removing sulphur and/or fluorine from the sludge have been found.