Vapor-phase polymerization is used for the first time to prepare ultrathin, polycrystalline conducting films of poly(3,4-ethylenedioxythiophene) (PEDOT). The polarized optical microscopy images (see figure) display the progress of crystalline growth at 30 degrees C: a) initial step of self-assembled PEDOT film formation (amorphous shape); b) nucleation; c) crystalline growth; and d) dendritic growth. The scale is 100 x 100 mu m(2).