Preparation of highly oriented layers of organic semiconductor – dithienothiophene derivative is described. The layers were obtained by zone-casting technique – a solution based one step method that does not require the use of preoriented substrates. Unidirectional alignment of the dithienothiophene derivative molecules in the zone-cast layers was confirmed by absorption and photoluminescence polarized spectra. Anisotropy of electrical properties was characterised by means of anisotropy of charge carrier mobility in field effect transistors (FETs). The FET devices were fabricated in bottom contacts – bottom gate configuration with the channel lengths parallel and perpendicular to the crystal growth direction, respectively. The FET mobility determined in the direction parallel to the zone-casting direction is ca. 1 order of magnitude higher than those in the perpendicular direction.