The use of correlation-gas chromatography to measure the vaporization enthalpy {A(I)(g)H(m)-(298.15 K)} of complex fuels is demonstrated using RP-1, JP-7, and JP-8, which are all rocket and jet fuels. Vaporization enthalpies of 308, 341, and 441 kJ/kg have been obtained assuming average compositions Of C12H23.4, C11H25, and C11H21, respectively. The H/C ratio in these fuels has been measured by H-1 NMR, and an average molecular weight has been determined using gas chromatography. Some variance in composition with the literature values has been observed. The vaporization enthalpies are compared to those in the literature and to values estimated for these compositions. The estimated values are discussed in terms of the composition of the fuel. The effect of detector bias in evaluating the mole fraction of each hydrocarbon present, as a function of size, is tested and determined to have a relatively small effect on the vaporization enthalpy.