Fe 2 O 3 nanoparticles were modified with 3-amino propyl trimethoxy silane (APTMS) by a sol-gel method. The surface chemistry of the Fe 2 O 3 nanoparticles was studied by Fourier transform infrared spectroscopy, which confirmed the successful grafting of the organic functional groups of APTMS onto the nanoparticle. Polyurethane composites were prepared by the incorporation of 1, 2, and 3 wt% of modified and unmodified Fe 2 O 3 nanoparticles. The surface morphology of the composites and distribution of the nanoparticles were investigated by field emission scanning electron microscopy. The composites were applied on the mild steel substrates. The adhesion strength of the composites was determined by a pull-off adhesion tester. The effect of nanoparticles on the electrochemical and corrosion behaviors of the coatings was investigated in a 3.5% NaCl solution, using electrochemical impedance spectroscopy and a salt spray test. Results showed that incorporation of 2 wt% modified Fe 2 O 3 nanoparticles significantly improved the corrosion resistance and recovery adhesion strength of the polyurethane coating compared to the blank coating and the one containing unmodified nanoparticles. KEY WORDS: 3-amino propyl trimethoxy silane, adhesion, electrochemical impedance spectroscopy, Fe 2 O 3 nanoparticle, polyurethane, salt spray ISSN 0010-9312 (print), 1938-159X (online) 15/000165/$5.00+$0.50/0 © 2015, NACE International CORROSION SCIENCE SECTION