The thermodynamic properties of novolac type phenolic resin blended with poly(ethylene oxide) (PEO) were investigated by the Painter-Coleman association model (PCAM). Equilibrium constants and enthalpy corresponding to the interaction between phenolic and poly( ethylene oxide) were calculated from the Fourier transform infrared spectroscopy of low molecular weight analogues in dilute solutions. The association parameters of the model compounds are transferred to the corresponding polymers, to predict the Gibbs free energy, phase behavior, and the degree of hydrogen bonding in the polymer blend. The heat capacity (C-p) and the excess heat capacity (Delta C-p) are used to verify the validity of PCAM model on predicting the thermodynamics properties of phenolic/PEO blend. It is found that the hydrogen bonding interaction dominates at moderate temperatures, which is outweighed by the dispersion force at higher temperature or high PEO compositions.