RP-1

RP-1 (alternately, Rocket Propellant-1 or Refined Petroleum-1) is a highly refined form of kerosene outwardly similar to jet fuel, used as a rocket fuel. Although having a lower specific impulse than liquid hydrogen (LH₂), RP-1 is cheaper, stable at room temperature, far less of an explosive hazard and far denser. RP-1 is significantly more powerful than LH₂ by volume. RP-1 also has a fraction of the toxicity and carcinogenic hazards of hydrazine, another room-temperature liquid fuel. Thus, kerosene fuels are more practical for many uses.