The synthesis of sulfonated cation-exchange matrices on novolac phenol-formaldehyde fibers followed by curing at preset pressures has yielded Polikon cation-exchange membranes with a uniform charge distribution and improved transport and electrochemical characteristics. It has been shown that the effect of pressure on the transport and electrochemical characteristics of Polikon membranes is nonlinear in character. These membranes can be recommended for use in dialysis and electrodialysis of solutions containing large organic cations.