Isomerisation process

A process for the production of triptane, said process comprising:

• isomerising a naphtha stream comprising a major amount of C5 to C8 hydrocarbons and being a C7 naphtha stream comprising at least one of n-heptane, 2-methyl hexane, 3-methyl hexane, ethyl pentane, 2,3-dimethyl pentane, 3,3-dimethyl pentane, 2,2-dimethyl pentane and 2,4-dimethyl pentane by contacting said feedstock with an isomerisation catalyst which is a superacid comprising HSO3F—SbF5 at a reaction temperature of −50 to 25° C., and a contact time of 0.01 to 150 hours, such that the triptane selectivity of the isomerisation reaction is at least 5 wt % as a proportion of said hydrocarbon feedstock.