Starting from 2,6-dithienyl pyrylium perchlorates, the pyrylation reaction was used to obtain 2,6-dithienyl-4-arylpyrylium salts. These salts yield stable monolayers at the air-water interface. Multilayers can be easily built up and films free of light scattering defects were obtained, Both the solution and the Langmuir-Blodgett films exposed to iodine vapor seem to lead to a molecular complex while, on treatment with FeCl3, oxidation and formation of oligothiophenes have been detected.