The selection of an hybrid MSF/RO desalination plant depends on many factors, such as capital costs, electricity consumption, water conversion rate and local requirements. In order to provide the necessary information for the decision process, stand-alone reverse osmosis or multi-stage °ash designs and alternative hybrid congurations must be characterized, optimized and compared on a sound basis. The aim of this paper is to present a computer-aided method, for the design and optimization of hybrid desalination systems. The optimization is carried out on technical, economical and environmental performance indicators in a multi-objective optimization framework. The approach is based on the conceptual decomposition of the MINLP design problem into two sub-problems. The network design problem is solved using conventional MILP solvers. The master problem, which consists in generating the list of available equipments, is solved using a multi-objective evolutionary algorithm. The results of this strategy are illustrated in an industrial case study.