It is shown that the three pure-component parameters in the Sanchez-Lacombe
equation of state can be determined from the critical temperature, critica
l pressure, and acentric factor. Vapor pressures from the equation have acc
uracy comparable to that obtained with the original Soave-Redlich-Kwong equ
ation and Peng-Robinson equation, even without introducing any temperature
dependence in the parameters. If temperature dependence is added to the San
chez-Lacombe epsilon energy parameter, the accuracy in the vapor pressures
can be improved.