High quality freestanding polyselenophene (PSe) films with conductivity as high as 2.8 x 10(-1) S cm(-1) were electrochemically deposited on stainless steel electrode from distilled boron trifluoride diethyl etherate (BFEE) containing 20 mmol 1(-1) selenophene. As-formed polymer films were homogenous and flexible, and could be easily cut into various desired shapes. Meanwhile, PSe films prepared in this medium showed good redox activity and high thermal stability in comparison with polythiophene and its derivative poly(3,4-ethylenedioxythiophene). To the best of our knowledge, this is the first case for the preparation of PSe films with high quality. (c) 2005 Elsevier B.V. All rights reserved.