Abstract: A new kind of thermodynamic properties is proposed which is designated by the name of b functionwhere θ1 and θ2 are θ functions of two reference fuels which, can be selected arbitrarily.The & function is dependent only on temperature and independent of hydrogen-carbon ratio of the fuel and fuel-air ratio for CnHm-air system. With the aid of the & function a set of generalized tables of thermodynamic properties has been worked out, which can be applied to obtaining the thermodynamic properties of CnHm-air system combustion products at any fuel-air ratio easily and exactly. A specimen of the generalized tables is given in this paper.