This diploma thesis deals with the general characteristics of membrane processes and separations. It includes a chapter on the history of development of the technology industry using membranes as a medium for separating chemicals based on their specific properties and also the importance of such processes at present. This work then introduces the basic principles of mass transport by membranes and describes various types of membranes and materials used for their production. It also deals with electromembrane separations, including electrodialysis. The practical part focuses on experimental separation of solutions of four sodium salts by means of electrodialysis. Based on the electrical current and conductivity measurements of these solutions in time during membrane separation are evaluated process parameters such as efficiency, energy consumption, transferred electrical charge, and mass of the sodium salt.