Disclosed is a process of fueling a rocket engine or air-breathing engine for a hypersonic vehicle with a high performance hydrocarbon fuel characterized by a hydrogen content greater than 14.3% by weight, a hydrogen to carbon atomic ratio greater than 2.0 and/or a heat of combustion greater than 18.7 KBtu/lb. The disclosed fuels generally have a paraffin content that is at least 90% by mass and a C12-C20 isoparaffin content of at least 40% by mass.