A computer aided system for synthesis, design and simulation of crystallization and fractional crystallization processes with electrolyte mixtures is presented. The synthesis methodology is based on the use of computed solubility diagrams for the corresponding electrolyte systems. For a specified crystallizer and product(s), the process flowsheet along with conditions of operation is determined while for a specified feed mixture and product(s), the process flowsheet together with the type of crystallizer is determined. In order to verify the "determined" flowsheet an option to perform steady state simulation is also provided. Examples highlighting the various features of the, computer aided system are presented.