The isomerization of n-butane to isobutane was examined over Pt/HM, Pt/HBEA and Pt/H-ZSM-5 zeolites and compared with that over pure H-zeolite forms. It was found that the presence of metallic platinum increases the n-butane conversion as well as the yield of isobutane. The increased platinum dispersion increases the n-butane conversion, but decreases the selectivity to isobutane by enhancing the cracking reactions. Additional experiments carried out under low pressures (0.2 kPa), followed by TPD of surface species, provided complementary results. FTIR spectra of surface species showed an increase of condensed aromatics predominantly in mordenites in agreement with their high deactivation.