One of the most important issues in the design of chemical plants is the trade-off between product recovery and costs, both investment capital and operating energy costs. High recovery of valuable products is desirable, but high recovery requires high separation costs. Distillation columns with more stages and higher reboiler duties are required as the specified recovery is increased. The optimum recovery depends on the difficulty of separation (relative volatility) and the value of the product. This paper quantitatively explores the impact of these parameters on the design of chemical processes.