−− Genetic Algorithms (GA) were implemented in a synthesis design procedure for cost optimal Heat Exchanger Networks (HEN). The procedure consisted of two coupled GAs: External GA to search the optimal HEN structure, and Internal GA to search the optimal split-fractions for each evaluated HEN structure. This design procedure was tested with five HEN synthesis cases; the configurations obtained were compared with other design procedures such as Pinch Method, Mathematical Programming (LP, MILP, MINLP and NLP models) and Stochastic methods (Genetics Algorithms, Tabu Search and Particle Swarm Optimization). In the cases 1 to 4, the ΔTmin value was taken from previous papers. In case 5 the ΔTmin value was optimized using a supertargeting routine available in the design algorithm proposed in this work. User-defined forbidden/desired matches can be easily implemented as target in the HEN design. Keywords−− Heat-Exchanger Network (HEN); Design synthesis; Stochastic Optimization; Genetic Algorithms.