This work introduces a systematic and analytical tray by tray method for the optimal and rigorous design of multicomponent distillation columns where, for a given feasible separation, convergence is almost always guaranteed in calculation times comparable to those used by commercial simulation packages. However, in this case the total number of stages and the optimal feed location are simultaneously determined. The distillate flow rate and the reflux ratio can be optimised in an outer loop providing the method a great flexibility. The commercial process simulator Hysys® has been used to solve the rigorous VLE using the available thermodynamic models such as NRTL, and MatLab® to implement the optimization algorithm. ; Póster presentado en Escape 22, European Symposium on Computer Aided Process Engineering, University College London, UK, 17-20 June 2012. ; Spanish Ministerio de Ciencias e Innovación (PPQ, CTQ2009-14420-C02-02).