The present invention provides a process for the conversion of synthesis gas to hydrocarbons comprising the steps of: a) contacting synthesis gas at an elevated temperature and pressure with a particulate Fischer-Tropsch catalyst in a Fischer-Tropsch reactor system to generate hydrocarbons comprising gaseous and liquid hydrocarbons; b) in a gas separation zone, separating a gaseous phase comprising saturated gaseous hydrocarbons from a liquid phase comprising liquid hydrocarbons and from the particulate Fischer-Tropsch catalyst; c) passing at least a portion of the separated gaseous phase to a dehydrogenation reactor where at least a portion of the saturated gaseous hydrocarbons are converted to unsaturated hydrocarbons; and d) recycling at least a portion of said unsaturated hydrocarbons back to the Fischer-Tropsch reactor system.