Microporous polyethylene films were formed in a process based on melt extrusion. Composite membranes were prepared by oxidative polymerization of conducting polymers (polyaniline, polypyrrole) or deposition from solution of polyelectrolyte (polyacrylic acid) in situ onto a polyethylene porous support. Multi-layer membranes consisting of different polymer layers were formed. Permeability, pore size distribution and mechanical characteristics of polyethylene microporous supports were measured. Surface and through electroconductivity, resistivity in electrolytes and transport properties of composite membranes modified by electroactive polymers were investigated.