A novel inherently conducting polymer, high-quality polyphenanthrene (PPh) films were synthesized electrochemically by direct anodic oxidation of phenanthrene (Ph) in boron trifluoride diethyl etherate (BFEE) containing a certain amount of trifluoroacetic acid (TFA). The oxidation potential of Ph in this medium was measured to be only 0.63 V versus SCE, which was greatly lower than that determined in acetonitrile + 0.1 mol L-1 BU4NBF4 (1.55 V vs. SCE). The electrolytes of BFEE containing TFA enable facile anodic oxidation of Ph monomer; however, similar oxidation using acetonitrile never produces such a polymeric material. PPh films obtained from this medium showed good redox activity and stability even in concentrated sulfuric acid. Dedoped PPh films were partly soluble in polar solvent such as CH2Cl2, acetone, tetrahydrofuran, and dimethyl sulfoxide. Fluorescent spectral studies indicate that PPh is a good blue-light emitter. The structure and morphology of the polymer were studied by UV-vis spectroscopy, FTIR spectroscopy, H-1 NMR spectroscopy, and scanning electron microscopy, respectively. The results of quantum chemistry calculations of Ph monomer and the spectroscopies of dedoped PPh indicated the polymerization mainly occurred at C-(9) and C-(10) positions. (C) 2007 Wiley Periodicals, Inc.