The effect of hydrophobic silicon carbide nanoparticles and carbon nanotubes on the mechanical and transport properties of MF-4SK perfluorinated cation-exchange membranes has been studied. It has been shown that the modification of the membranes with a small amount of silicon carbide and carbon nanotubes enhances both their mechanical strength and selectivity of transport processes. An increase in the dopant concentration leads to deterioration of these parameters and the destruction of the membranes. This change in the properties is attributed to the implantation of nanoparticles into the hydrophobic membrane matrix, which results in a decrease in its elasticity.