Correlations are presented for the viscosity and Prandtl number of hydrocarbon-air combustion products for the temperature range 500 K to 4000 K, pressure range 1 to 100 atm, and fuel-air equivalence ratio range of 0 to 4. The required thermodynamic properties for calculating the thermal conductivity from the Prandtl number,cpand γ, are also given. The principal advantage of these correlations is computational speed; they have been developed primarily for internal combustion engine performance calculations.