The composition of Navy Jet fuel JP-5 was determined using gas chromatography­(GC)-electron impact mass spectrometry and GC × GC/(flame ionization detection) to contain by mass 21% linear alkanes, 29% cycloalkanes, 32% isoalkanes, and 18% aromatic compounds. Various quaternary mixtures of n-dodecane, n-butylcyclohexane, n-butylbenzene, and 2,2,4,4,6,8,8-heptamethylnonane were prepared as possible surrogates for this jet fuel and analyzed for density and viscosity (253 to 333) K, speed of sound (288 to 333) K, surface tension (294 ± 1 K), and flashpoint. Deviation cutoffs for “matching” the JP-5 based on previous studies and fuel specification were ±1.7% for density, ±1% for speed of sound, ±3.5% for bulk modulus, ±2.6% for viscosity, ±2.2% for surface tension, and ±10% for flash point (minimum of 333 K). Seven quaternary mixtures met these cutoffs. Three had compositions that were comparable to the JP-5 and would be good candidates for engine testing. All mixture excess molar volumes showed a trend of increasing to a maximum and then decreasing as the concentration of n-butylbenzene increased. Viscosity deviations ranged from (−0.03 to −0.48) mPa·s.