TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The stream as obtained in the second step has the temperature of 1-40 degrees C, preferably 2-20 degrees C above the temperature at which carbon dioxide freezes from the feed stream. In the second step, the pressure and/or the temperature of the feed stream are lowered to obtain a stream having a pressure of 40-60 bars and a temperature of -60 to -80 degrees C. In the cooling step, the stream is cooled: to -75 to -110 degrees C, preferably -80 to -105 degrees C; and by isenthalpic expansion, preferably isenthalpic expansion over an orifice or a valve (preferably a Joule-Thomson valve). The feed stream provided in the first step is obtained by cooling a feed gas stream which comprises the gaseous product and gaseous contaminants by: nearly isentropic expansion, especially by means of an expander (preferably a turbo expander or a Laval nozzle); by isenthalpic expansion, preferably isenthalpic expansion over an orifice or a valve (especially a Joule-Thomson valve); and/or by isobaric cooling, preferably isobaric cooling using at least one heat exchanger. The feed stream provided in the first step is obtained by cooling the feed gas stream in a step (a) by nearly isentropic expansion, especially by means of an expander, preferably a turbo expander or a Laval nozzle, and/or by isenthalpic expansion, preferably isenthalpic expansion over an orifice or a valve, especially a Joule-Thomson valve, to a first temperature, and cooling the stream so obtained in a step (b) by isobaric cooling, preferably isobaric cooling over at least one heat exchanger, to a second temperature which is lower than the first temperature. The feed stream provided in the first step is obtained by cooling the feed gas stream in a step (a1) by isobaric cooling, preferably isobaric cooling over at least one heat exchanger, to a first temperature, and cooling the stream so obtained in a step (b1) by nearly isentropic expansion, especially by means of an expander, preferably a turbo expander or a Laval nozzle, and/or by isenthalpic expansion, preferably isenthalpic expansion over an orifice or a valve, especially a Joule-Thomson valve, to a second temperature which is lower than the first temperature. The first temperature in step (a) or (a1) is -75 to 15 degrees C, and the pressure of the stream so obtained is 40-150 bars. At the first temperature liquid phase contaminant is formed as well as a gaseous phase rich in gaseous product. Preferred Components: The feed stream comprises more than 80 vol.%, preferably 100 vol.% of liquid phase. The feed gas stream is a natural gas and comprises 10-90 vol.% of carbon dioxide, 0.1-60 vol.% of hydrogen sulfide, and 20-80 vol.% of methane. EXAMPLE - No suitable example given.