The inhibitory action of 3(trimethoxysilyl)propanethiol-1 (TMSPT) on copper corrosion in NaCl 3.5% solutions at pH 6.5, at 25 degrees C and with an initial oxygen content of 6.5 ppm was examined. Different amounts of TMSPT (0.5 x 10(-3), 1.1 x 10(-3), 2.0 x 10(-3), 2.7 x 10(-3)) M were added to NaCl solutions. Weight loss and electrochemical tests show that the inhibitory action of TMSPT increases with increasing TMSPT concentration, and decreases with increasing the exposure time. TMSPT acts as an anodic inhibitor (by forming an adsorption film on copper surfaces) as well as a cathodic inhibitor (by reducing dissolved oxygen content in corrosive solutions).