Poly-vinylethers (PVE) containing triethoxy-silyl groups in the side-chains were synthesised and crosslinked during membrane processing in the presence of LiCl4. The electrolytic membranes had excellent dimensional stability and showed promising ionic conductivity, approaching the value of 10(-5) S/cm at 25 degrees C. The effect of the side chain length, in term of EO units, and of the salt concentration on conductivity was also investigated.