TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The step (a) is performed by subjecting the hydrocarbons to at least one reforming reaction (4) and/or at least one shift reaction (5), where the reactions are carried out in a cascade in the indicated order. In the method: the hydrogen gas produced from the hydrocarbons is introduced into the syngas before a gas treatment step, in which carbon dioxide is removed from the syngas; the carbon dioxide is separated from the syngas by membrane filtration, pressure swing absorption or by washing with a liquid including methanol that is capable of absorbing carbon dioxide, where significantly all of the carbon dioxide contained in the gas is removed before it is fed into the FT reactor; the pressure of the syngas is increased to the pressure of the FT reaction immediately before, during or after the gas treatment step; the hydrocarbons of the off-gas of the FT reactor comprise saturated or unsaturated, linear or branched 1-4C hydrocarbons, preferably saturated 1-4C hydrocarbons including methane; at least a part, preferably a majority (based on the volume) of the recovered gaseous hydrocarbons is recycled from the FT reactor to the syngas via at least one step, in which light hydrocarbons, primarily methane, are converted to hydrogen; and external light hydrocarbons including 1-4C hydrocarbons (methane) are fed into the recovered gaseous hydrocarbons that are being recycled to the syngas before the hydrocarbons are subjected to a step for converting light hydrocarbons into hydrogen, where the ratio of external methane to the methane present in the recycled gas is, based on volume, 1:100-100:1, preferably 1:20-20:1. The method comprises: gasifying the raw-material in the presence of oxygen to produce a gas containing carbon monoxide, carbon dioxide, hydrogen and hydrocarbons possibly together with inert components; feeding the gas obtained by gasification of the raw-material into a reformer; reforming the gas in the presence of oxygen at a temperature in excess of 850?C to increase the ratio of hydrogen to carbon monoxide in a gaseous effluent of the reformer to 0.5-1.7; withdrawing the gaseous effluent from an outlet of the reformer; cooling the gaseous effluent to below 500 degrees C; washing the gaseous effluent in a water scrubber at a pressure of 80-4000 kPa using water having a temperature of 30-80 degrees C, preferably 40-60 degrees C to remove ammonia, hydrochloride and particles; further removing hydrogen sulfide and carbon dioxide in a one step or two step process; and further increasing the hydrogen-to-carbon monoxide ratio of the gaseous effluent to 2 by introducing hydrogen. EXAMPLE - No suitable example given.