The influence of the conditions of sulfuric-acid activation of the Narynkol' clay as a catalyst matrix on the properties of zeolite-containing platinum catalysts for n-hexane isomerization was studied. The activity of specimens correlated with the amount of alkali-metal cations in them and clay crystallinity. The catalysts based on the activated Narynkol' clay exhibit high activity and selectivity for isomeric alkanes under mild conditions and are superior in main characteristics to alumina, which is traditionally used in industrial isomerization units.