In the presence of a polyfunctional zeolitic catalyst based on an X (FAU)-type synthetic zeolite. n-butane is transformed into a mixture of C-3-C-5 isomers containing 25 mol % isobutane. The distribution of the isomeric product composition depending on the reaction temperature and the catalyst operation time allows schematic mechanisms to be proposed for the occurring reactions. The satisfactory yield of isobutane, high purity of the products, and absence of harmful wastes from the entire catalyst preparation and testing cycle (including regeneration) in combination with the capability of multiple regeneration of catalytic activity open up a possibility for the wide industrial application of these catalysts.