The hydroisomerization reaction of n-octane at atmospheric pressure and a temperature of 230A degrees C on platinum-containing catalysts with a combined micro-mesoporous structure synthesized on the basis of MOR and BEA zeolites was studied. The influence of the nature of zeolite, the relative amount of micropores, the platinum content, and the Si/Al ratio on the catalytic activity was examined. The microporous materials showed a considerably higher n-octane conversion and a higher isomerization selectivity as compared to both starting zeolites and mesoporous catalysts. It was found that the BEA-based micro-mesoporous materials are more active and selective than mordenites. An increase in platinum loading from 0.2 to 0.7 wt % leads to a rise in the yield of octane isomers, and a further increase in the platinum content does not result in a substantial change in the characteristics of the processes. It was shown that a change in the Si/Al ratio has a considerable effect on the formation of polybranched C(8) isomers.