Molybdenum was used as an alternative to sulfate as promoter of zirconia for alkane isomerization reactions. It has similar effects to sulfate, tungstate and phosphate ions, modifying the physicochemical properties of unpromoted zirconia. Mo-promoted zirconia catalysts do not show any activity for n-C-4 isomerization. For n-C-7 isomerization, the catalytic activity depends on Mo content, crystalline structure of the support and the molybdenum oxospecies present on the surface of the catalysts.