A process for the preparation of essentially linear and saturated hydrocarbons from natural gas (1), comprising the following successive steps, the order of steps (b) and (c) being exchangeable or said steps being capable of being conducted simultaneously: (a) producing (6) synthesis gas (7) by treatment of said gas, (b) mixing an effluent comprising at least the synthesis gas (7) obtained from the preceding step and an effluent (4) comprising mainly C.sub.2 -C.sub.4 hydrocarbons, (c) cooling an effluent comprising at least the mixture obtained from the preceding step, (d) transforming the effluent (8) obtained from step (c) in a cracking zone (10), (e) separating (12) the effluent obtained at step (d) into an effluent comprising mainly water (13) and an anhydrous effluent (14), and (f) transforming (15) the effluent obtained from step (e) (14) by a Fischer-Tropsch synthesis.