The hydroisomerization of a C-10-C(13)n-alkane mixture was investigated over six bifunctional platinum-containing zeolite catalysts with 10- and 12-membered-ring pore systems. The catalysts with 12-membered-ring zeolites are more active than those with 10-membered-ring zeolites. In contrast, higher yields of the desired monobranched isomers are obtained over the 10-membered-ring zeolites due to shape-selectivity effects. For the 10-membered-ring zeolites, higher reaction temperatures are required for achieving the maximum isomer yields, which leads to more cracking products compared to the 12-membered-ring zeolites.