In this work, the physical properties of binary mixtures of n-heptane and 2,2,4-trimethylpentane were measured. Density and speed of sound were measured at temperatures ranging from (293.15 to 338.15) K, and viscosity was measured at temperatures ranging from (293.15 to 333.15) K. At 298.15 K, pure component values for heptane of 679.61 kg.m3, 0.389 mPa.s, and 1130.1 m.s-(1) for density, viscosity, and speed of sound, respectively, agree with literature values. Similarly for 2,2,4-trimethylpentane, the values of 687.70 kg.m3, 0.501 mPa.s, and 1081.7 m.s-(1) for density, viscosity, and speed of sound, respectively, agree with literature values. Density mole fraction and temperature data were fit to a second-order polynomial. Bulk moduli ranged from (551.7 to 907.1) MPa over (293.15 to 338.15) K. Viscosity mole fraction data were fit using the three-body McAllister model, while the viscosity deviations were fit to a RedlichKister type equation. For the mixtures, an increase in mole fraction of 2,2,4-trimethylpentane resulted in an increase in density and viscosity and in a decrease in speed of sound, bulk modulus, and surface tension. Increases in temperature decreased density, viscosity, speed of sound, and bulk modulus. At room temperature, the surface tension values ranged from (18.7 to 20.3) mN.m-(1). These data can be used by researchers who are modeling the combustion process of mixtures of primary reference fuels and are modeling the physical properties of fuels.