Using in situ FTIR attenuated total reflection (ATR) spectroscopy, the electrochemical polymerization process of 2,2’-thienylpyrrole monomer in electrolytes containing LiClO4, Bu(4)NClO(4), Bu(4)NBF(4) and Bu(4)NPF(6) was investigated. Poly(thienylpyrrole) layers with different physical properties are produced and the vibrational modes of the IR absorption bands are discussed. The thienylpyrrole monomer exhibits different oxidation potentials in different electrolytes, Monomer and electrolyte adsorption on the electrode/electrolyte interface, chemical and electrochemical polymerization of the monomer are clearly observable at definite potentials. The maximum of an electronic absorption changes with the potential and the electrolyte composition. A polymer with a well-defined conjugation length is produced and charge-carrying species (polaron or bipolaron) emerge in the polymer chain. The polymer film undergoes a change from the non-conducting form to the conducting form at higher positive potentials. The results show the capability of in situ FTIR-ATR spectroscopy for yielding important information on the elucidation of the polymerization reactions of the thienylpyrrole monomer.