A carbided molybdena on sulfated zirconia support has been prepared by in situ exposure to a methane/hydrogen mixture at 650 °C and the characteristics established using N2 adsorption and X-ray diffraction. The activity of the catalyst in the hydroconversion of C6 to C9 n-alkanes was investigated in the temperature range 350–450 °C at 1 atm pressure. Activity and selectivity were found to show strong dependence on the choice of n-alkane with reaction rates found to be higher for the shorter alkanes. n-Hexane and n-heptane were hydroisomerised to the corresponding C6 and C7 isomers with high selectivity while the higher alkanes, especially nonane, produced mainly hydrocracking products. The catalyst offers a potential system for the upgrading of light naphtha range paraffins.