An effective-medium theory of a random mixture of metal and solid elec
trolyte particles is developed to describe the bulk ac conductance of
the composite. It predicts a 4 to 6 orders of magnitude enhancement of
the dielectric permeability of the composite near the percolation thr
eshold for electronic conductivity. As the frequency increases, the en
hancement falls to the level of a metal-dielectric composite, as the r
ole of the double-layer capacitance of the blocking interfaces between
metal and electrolyte grains diminishes. Analytical expressions are o
btained for the conductivity and dielectric function over the whole ra
nge of relative concentrations and in a broad frequency range.