A quartic equation of state (EOS) [Yun et al., Fluid Phase Equilibr. 2001; 187-188: 275-298] is used for predicting critical properties of pure substances. Parameters in the EOS are rewritten as functions of temperature (T in K), and there are totally eleven substance-specific constants in the functions for each substance. Data of few experimental points including saturated vapour pressure, saturated liquid molar volume and evaporation enthalpy at some temperatures are required in this study to determine the substance-specific constants in the EOS, while the knowledge of molecular structure is not necessary.