The microstructural aspects of polyacrylonitrile(PAN)-iodine complex made from stretched FAN film were studied by infrared spectroscopic. volumetric. mechanical and dielectric characteristics. The complex shows two very different properties (dependent on its iodine content, which is supplementary to X-ray data in view of the fact that a crystalline phase transition is confirmed to occur depending on the iodine content. The iodine sorption of up to 30 weight % makes the PAN chains rigid by sticking to backbone chains, and bulky by interrupting intermolecular bonds of PAH. The iodine sorption of beyond 80 weight % increases weak intermolecular bons and decreases the free volume of the PAN-iodine complex film seriously. Thermal mobility of PAH chains decreases, but molecular motions of side groups of PAH increase with strengthening their dipole moment by influence of the electrophilic iodine ions.