Electromembrane systems with cation-exchange membranes and solutions of different amino acids were studied by means of conductometric and chromopotentiometric methods. Conductometric method was adapted to membrane systems with amino acids. Electric current was passed lengthwise through a membrane. Three mechanisms of membrane electrotransport were proposed for amino acids. The process of charge transfer within a cation-exchange membrane is provided by: i) H+ ions; ii) amino acid cations; iii) both of the ions. Chronopotentiometric method was developed to study electroosmotic processes in electromembrane systems with amino acids. The rate of electroosmotic flow was included into the equation of electromass transfer for a membrane system. Water transport numbers were calculated for electromembrane systems with cation-exchange membranes MC-40, MF-4SK and amino acid solution.