Many major oil-and-gas fields in USA, Canada, Russia and other countries keep sulphur, oxygen, and nitrogen-containing chemicals along with general hydrocarbon mass. These impurities complicate the processing of natural raw hydrocarbons material to fuels and chemicals contaminating them and decreasing their consuming properties. The amount of natural mercaptans that can be potentially isolated this way is dozens of thousand tones per year. An example is the processing of gas condensate from Orenburg (Russia), Crossfield and Line Creek (Canada), Lac (France) and many other fields. The present book describes the scientific basis for isolation and possible utilisation of the light fraction (C2-C5) of mercaptans contained in gas condensate from Orenburg, Russia.