Generally the ion exchange membrane consist of polymer networks which have positive or negative ionic charged fixed group anchored in their structure. Its charged fixed ion groups are negative, the polymer membrane is selective of cations, whereas positive charged groups are selective of anions. Transport processes through membranes cannot be considered as thermodynamic equilibrium processes and therefore only the thermodynamics of the non-equilibrium processes can be used to describe membrane transport. In non-equilibrium processes (and thus in membrane transport) free energy is dissipated continuously (if a constant driving force is maintained) and entropy is produced. Using the entropy production term, fluxes can be expressed as a linear combination of all driving forces with corresponding phenomenological coefficients.