Composite materials based on MF-4SK membranes (Plastpolimer, Russia), a membrane foil (Mega, Czech Republic), and phosphate-modified zirconia been synthesized; the transport properties of the composites in the proton and potassium forms have been studied. It has been found that the degree of doping of the heterogeneous membranes can be significantly higher than that of the homogeneous samples. It has been shown that the surface modification of zirconia with phosphate groups results in increase in the conductivity (from 0.0029 to 0.011 S/cm) and selectivity of transport processes improvement (from 0.068 to 0.009) in the membrane foil. Differences in the observed values of conductivity and mutual diffusion coefficient of the membranes in the hydrogen and potassium forms have been discussed taking into account the possible ion transport mechanisms.