A method is proposed for the computer-aided molecular design of solvents for extractive distillation. The method is based on a genetic algorithm and uses UNIFAC to estimate relative volatilities. Joback＇s group contribution methods are used to estimate boiling and freezing points. A number of enhancements, including seeding, evolving fitness functions, and biased gene selection have been included. The method has been implemented in a computer program that runs on a standard desktop computer. A number of industrially significant systems were investigated, and the predicted solvents compare very favorably with those that are currently in use.