A comprehensive investigation of the chemical equilibrium thermodynamic properties (M, CP, h and s) of the products of combustion of ethanol-octane and methanol-octane blends in air is presented. Complete spectrums of fuel blends (ranging from pure octane C8H18 to pure ethanol C2H5 OH or methanol CH3OH), fuel-air mixtures (from very lean, ϕ = 0.15 to very rich, ϕ = 2.0) and combustion products temperature, T and pressure, P (in the ranges of 600-5000 K and .5-1000 ata) are examined. Mole fractions of the most important 16 product species are calculated and discussed. The extent of disscoiation and energy loss terms are defined, evaluated and discussed.The real gas effect on these properties in the low temperature range (600 - 2400 K) when evaluated by correlated equations of Ref. (1)* are found to be insignificant.