In this paper, a novel and efficient way of designing the pervaporation sector of a hybrid distillation/pervaporation process to minimize its total cost, using rigorous models of the azeotropic distillation column and pervaporation modules, is presented. Within this framework, the strategy to select the minimum required membrane area is the key feature, together with the selection of the operating temperatures between the membrane modules and the operating variables of the distillation column. The number of membrane modules required is evaluated by integrating the differential equations until the separation target of the pervaporation sector is achieved. Am underapproximation of the bubble-point temperature of the interstage streams is presented to calculate the heating temperature between membrane modules. The numerical results show the significant cost reduction achieved with the strategy developed for the optimum design of hybrid distillation/pervaporation systems.