We have designed and synthesized a new polymer, which could be used in the organic thin film transistor (OTFT). Poly[2,6-bis(3 '-dodecythiophene-2 '-yl)anthracene] (PDTAn), which is composed with anthracene moiety and dodecyl alkyl thiophene, was synthesized by oxidative polymerization using iron (III) chloride. The mole ratio of FeCl3 and monomer (4.2:1), keeping low temperature during the initiation reaction, amount of solvent, and dropping order were very important for oxidative polymerization without crosslinking. The molecular weight of the polymer (MW) was measured to be 40,000 with 2.85 of polydispersity index by GPC. The physical and optical properties of the polymer were characterized by differential scanning calorimetry (DSC), cyclic voltammetry (CV), and optical absorption and photoluminescence (PL) spectroscopy. A field-effect mobility of 1.1 X 10(-4) cm(2) V-1 S-1, a current on/off ratio of 10(5), and the V-th at -15.2 V had been obtained for OTFTs using this polymer semiconductor by solution coating. (C) 2008 Wiley Periodicals, Inc.