Vapor-liquid equilibrium is predicted by using the Soave modification of the Redlich-Kwong equation of state (EOS). The concept of equal fugacities is used to calculate the equilibrium constant, K-i = y(i)/x(i), then, it is shown how the Murphree tray efficiency can be applied on the liquid or the vapor phases to modify that constant. The derivatives needed are calculated numerically, and it is shown that for absorbers and distillation columns, Murphree tray efficiency applied this way can be used to simulate the actual number of stages.Murphree tray efficiency values can be specified for one, several or all of the components on any Stages of a column.A dehydration example is shown, the dew point depression values of a mixture of water-gas, using a triethylene glycol solution for dehydration purposes, are calculated by incorporating the method into a process simulator program called PROSIM(R) and compared with the values reported in the literature.