The combination of a nonlinear programming method with the simulated annealing procedure allows the automatic synthesis and optimization of reactor networks. This requires the search of the optimal solution within a superstructure containing the totality of all potential and feasible configurations to provide the optimal solution, Due to the complexity and combinatorial aspect of this type of process, the definition and the mathematical formulation of a feasible scheme of the superstructure is not a trivial task, The proposed synthesis strategy is based on the mathematical representation of any structure through an incidence matrix., The presented procedure is based on this incidence matrix and is illustrated by some significant examples.