The highest efficiency, around 70 % in single-step extraction exhibited NMP. NMP was evaluated as having the best chance to be used in industry. It was shown that for some transformer oils the separation of corrosive sulfur with the common technique of filtration through a layer of commercially available sorbent (for example Fuller’s earth) is totally inadequate. However, extraction efficiency of DBDS from contaminated transformer oil with the help of NMP is sufficiently high over 99 % and feasible in a fair time of about 20 minutes. The remaining concentration of DBDS after single-step extraction from transformer oil containing up to100 ppm DBDS was low enough (approx. 0.1 ppm or non-detectable). Detection of corrosive sulfur in transformer oil after extraction with NMP has been also performed by Siemens test method (IEC 62535) and by updated ASTM 1275B proposed by CIGRE Covered Conductor Deposition test method and was negative. It is possible to consider the transformer oil after the extraction procedure as corrosive sulfur free. Traces of solvent in the oil after extraction were quantitatively separated from treated oil by purification via simple liquid-solid extraction with commercial Si-Al-Mg based inorganic sorbent containing attapulgite.