The corrosion resistance of steel panels coated with pentasiloxanes has been evaluated by electrochemical impedance spectroscopy (EIS) during exposure to 0.5 N NaCl. Two fluorinated and a nonfluorinated pentasiloxane have been prepared to develop nontoxic polymer coatings with improved biofoul release properties. Depending on the terminal epoxy group type, two different cross-linking/cure chemistries were utilized. The first type of cross-linking reaction involved room-temperature UV cure with a photoacid catalyst and the second cross-linking reaction was phenol-catalyzed thermal cross-linking with alpha, omega-diaminoalkanes [NH2-(CH2)(n)-NH2]. The EIS data suggest that the nonfluorinated pentasiloxane provided better corrosion protection than the two fluorinated pentasiloxanes and that room-temperature UV cure with a photoacid catalyst provides better corrosion protection than phenol-catalyzed thermal cross-linking. (c) 2005 The Electrochemical Society. All rights reserved.