Abstract: The invention relates to a doped polyacetylene film for forming an organic semiconductor or even a conductor of a metallic type. It serves to make the doping more homogeneous and improves the stability over a period of time. The process consists of using as the dopant a salt of an element such as chrome, nickel, iron, titanium, tungsten, or molybdenum belonging to the transition metals, or a salt of an element such as europium or ytterbium belonging to the lanthanides. Doping takes place by immersing the film in a solution having a low dopant concentration, e.g. in toluene, and maintaining the system at low pressure and ordinary temperature for a period of a few days, as a function of the desired doping level and conductivity.