The main objective of this work is the analysis and optimisation of azeotropic distillation columns, when a liquid side stream with the distributing non-key component is treated in a pervaporation membrane and the retentate is recycled to the column. The objective is to separate the pure distributing non-key component using a pervaporation. membrane, thus helping to improve the purity in the top and/or bottom products. The operating conditions of the column such as reflux ratio, product and side draw flowrates and pressure are selected optimally to minimise the operating cost of the hybrid system. The simulation of the pervaporation membrane units is implemented solving the differential-algebraic equation system of mass transport and energy balances. The optimisation of the operating conditions of the azeotropic distillation column in the hybrid distillation/pervaporation system for Methyl tert-butyl ether production is presented. Numerical results with a significant reduction in the operating cost are reported.