NOVELTY - The liquid fuel cell fuel comprises synthetic products of Fischer-Tropsch processing including paraffinic and optionally iso-paraffinic hydrocarbons and less than 0.001 wt.% sulfur.    USE - For use in operating a fuel cell to produce electrical power.    ADVANTAGE - The fuel provides, on a per unit volume basis, high yields of hydrogen from a fuel cell fuel processor. A fuel cell power generation station or buses using synthetic gasoline-range paraffin can generate greater than 87% more energy from a given volume of fuel than from the same fuel cell using methanol, based on non-ideal conversion to hydrogen and carbon monoxide. Vehicles using the fuel can travel almost twice as far as the same vehicle using methanol or methane. It can be handled in the same fuel distribution systems for distributing and dispensing internal combustion engine fuels. It eliminates complications of gasoline reforming for fuel cells and the task or removing sulfur from hydrogen feed stream before it can damage the fuel cell.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (a) the production of a fuel cell fuel, comprising preparing a Fischer-Tropsch product, and separating from the product a light portion comprising 5-20 or 28C material having at least 77 wt.% normal and iso-paraffins, less than 20 wt.% olefins, less than 9 wt.% alcohols, less than 0.001 wt.% sulfur, and less than 5 wt.% aromatics;    (b) a fuel cell system or a system powered by a fuel cell, comprising the inventive fuel as the sole fuel or as a blend containing the fuel and another fuel component; and    (c) a conversion system for converting light hydrocarbons into heavier hydrocarbons, comprising a synthesis gas subsystem for receiving light hydrocarbons and, optionally, other synthesis gas forming reactants, e.g. steam and/or oxygen-containing gas, and for developing a synthesis gas from it; a synthesis subsystem fluidly coupled to the synthesis gas subsystem for receiving synthesis gas and for producing heavier hydrocarbons; a fuel cell processor coupled to the synthesis gas subsystem for preparing the synthesis gas for use in a fuel cell as a hydrogen-containing gas; and a fuel cell coupled to the processor to receive a hydrogen-containing gas and produce electrical power.