A new equation of state applicable to lower reduced temperatures than the BWR equation of Starling and Han (BWRS equation) is proposed, adding four coefficients to their equation of eleven coefficients. Thermodynamic properties predicted by the two equations, such as density, enthalpy, isobaric heat capacity, f ngacity coefficient, vapor pressure, and vapor-liquid equilibrium, are compared to test the validity of the new equation of state. The ranges in which thermodynamic properties can be predicted, within about 10 % error, are extended down to 0.35 or below at reduced temperatures with the new equation. The limit for the prediction of saturated fugacity and vapor pressure for a pure substance, for instance, can be lowered from 0.47 with the BWRS equation to 0.32 with the new equation of state.