A process to prepare a paraffinic hydrocarbon from a solid carbonaceous feedstock, preferably coal by performing the following steps,(a) feeding an oxygen comprising gas and the carbonaceous feedstock to a burner positioned horizontal and firing into a reactor vessel,(b) performing a partial oxidation of the carbonaceous feedstock in said burner to obtain a stream of hot synthesis gas which flows upwardly relative to the burner and a liquid slag which flows downwardly relative to the burner,(c) cooling the hot synthesis gas by first cooling the gas to a temperature of between 500 and 900.degree. C. by injecting a gaseous or liquid cooling medium into the synthesis gas and subsequently second cooling the gas in to below 500.degree. C. by directly contacting with water, (d) separating solids from the cooled synthesis gas by means of a water scrubbing process step, (e) performing a water shift reaction on at least part of the scrubbed synthesis gas, (f) separating sulphur compounds, carbon dioxide and other possible impurities from the shifted gas to obtain a purified synthesis gas, and (g) performing a Fischer-Tropsch synthesis using the purified synthesis gas of step (f) to obtain a synthesis product comprising paraffinic hydrocarbons.