In contrast with the HF/SbF5 superacid system and despite its strong acidity (H-0 = -14.1), CF3SO3H is not able to protonate reversibly small alkanes. At room temperature propane and n-butane do not exchange their hydrons for deuteriums with deuterated triflic acid. The H/D exchange occurring between isobutane and the CF3SO3D acid is regiospecific as observed in weaker acids such as D2SO4 or solid acids such as sulfated zirconia or zeolites. In the same way, the formation of C-5 alkanes during C-4 isomerization is indicative of a classical bimolecular process, in the presence of carbon monoxide, isomerization as well as H/D exchange are suppressed due to chemical trapping of the carbenium intermediates.