Interfacial tension between tetradecane (CH3(CH2)(12)CH3) (melting point, 5.8 degrees C; density, 770 kg m(-3) (6 degrees C)) and ethylene glycol (CH2OH . CH2OH) (density, 1119.5 kg m(-3) (10 degrees C)) water solution was measured by means of the pendant drop method. The measurements were performed for various temperatures of 10 similar to 50 degrees C and mass concentrations of the water solution of 0 (water) similar to 100 mass%. It was clarified that the interfacial tension decreased exponentially in about 60 min after creation of the pendant drop. This paper reports the value of the static interfacial tension obtained when the temporal change of the interfacial tension with time ceases due to the equilibrium of mass diffusion between both liquids. The value of interfacial tension decreases linearly with an increase in temperature and mass concentration of the water solution. As a result, the empirical equation of static interfacial tension was derived in terms of temperature and mass concentration of the water solution.