A hydrocarbon fuel composition which is suitable for sue in a fuel cell
apparatus and an internal combustion engine comprises at least one
saturated aliphatic hydrocarbon having 4 to 12 carbon atoms, and is
characterised by an olefin content of less than 20% by volume, an
aromatics content of less than 42% by volume, a final boiling point (fop)
of less than 215.degree. C., and a sulphur content of less than 20 ppm.