Through tetrabutylammonium bromide poisoning of acid sites on the external crystal surface of the zeolite framework of palladium-containing hexane isomerization catalysts, the important role of these sites in the formation of 2,2-dimethylbutane was revealed. From the viewpoint of selectivity for 2,2-dimethylbutane, these sites should be preserved to the maximum degree upon introducing palladium into the acid zeolite support. It was shown that the modification of acid zeolite forms with palladium dichloride is preferable to that with tetraamminepalladium dichloride.