To suppress steel corrosion at elevated temperature and in humid condition, silane coupling agents N-beta-aminoethyl aminopropyltrimethoxysilane (AAPS), gamma-glycidoxypropyltrimethoxysilane (GPS), and bis[3-(trimethoxysilyl)-1-phenylpropyl]tetrasulfide (RC-2) were introduced as primers into an epoxy/steel system. Silane coupling agents and epoxy were coated onto the steel surface using the solution casting method. The polymer degradation and steel corrosion formation after heat and humid treatment were investigated by Fourier transform infrared reflection and absorption spectroscopy (FTIR-RAS) and scanning electron microscopy (SEM). Compared to various silane treated epoxy/steel systems, the AAPS-treated epoxy/steel (AAPS/epoxy = 6 : 4) system suppressed steel corrosion at 400 degrees C for 10 min in air and for 5 days at 60 degrees C in 100% relative humidity. This is due to the formation of Si-O-Si linkage and Fe-O-Si bond on steel surface, which are resistant to water diffusion and thermally stable at elevated temperature. The relationship between chemical bonding at the steel-epoxy interface and corrosion protection on the steel surface was also investigated.