Electrochemically grown films of polyaniline, polypyrrole, polythiophene, and poly(ethylenedioxythiophene) were treated with alkane- and fluoroalkanethiols for 1-24 h. The resulting films showed surface energies and polarities similar to glass slides coated with monolayers of the corresponding alkyl- and fluoroalkylsilanes. Treatment of the polyaniline, polypyrrole, and, to a lesser extent, poly(ethylenedioxythiophene) films resulted in covalent bonding of the thiol to the polymer backbone as evidenced by X-ray photoelectron, energy-dispersive X-ray, and electronic spectroscopies. Polypyrrole and poly(ethylenedioxythiophene) films showed reduced electroactivity upon treatment, while the derivatized polyaniline could be returned to a conducting state. Polythiophene primarily oxidized the thiols to soluble products, leaving the polymer backbone unaffected.