The invention relates to an installation and a process for the production of liquid fuels starting from a solid feedstock that contains the organic material in which: a) the solid feedstock is subjected to a gasification stage so as to convert said feedstock into synthesis gas, b) the synthesis gas is subjected to a purification treatment, c) the purified synthesis gas is subjected to a conversion stage that comprises the implementation of a Fischer-Tropsch-type synthesis so as to convert said synthesis gas into a liquid effluent and a gaseous effluent, d) the liquid effluent is fractionated so as to obtain a gaseous fraction, a naphtha fraction, a kerosene fraction and a gas oil fraction, and e) at least a portion of the naphtha fraction is recycled in gasification stage a).