The preparation of multilayered structures with polyconjugated systems has been performed with a modified poly (3-alkylthiophene) containing an oxygen atom in the side chain as reported in a previous paper [1]. The polymeric backbones in the obtained Langmuir-Blodgett structures have been found to be oriented in the dipping direction and the conjugation length so far obtained is higher with respect to that previously reported [ 1]. Alternated multilayered heterostructures formed by two layers of a diacetylenic cadmium salt and one layer of the above-mentioned polymer has been prepared obtaining, after photopolymerization, alternated heterostructure between poly-diacetylene and poly(3-alkylthiophene), A preliminary investigation of the electronic behavior of this heterostructure is reported.