Polyethylene terephthalate waste (PET) was depolymerized by triethanolamine into glycolyzed product (GT), followed by esterification with bromacetic acid in the presence of manganese acetate as a catalyst to give (GT-Br). The obtained ester was reacted with thiourea to give thiol derivative (GT-SH). The effectiveness of the synthesized compound as corrosion inhibitor for API XL65 carbon steel, in 2 M hydrochloric acid solution was investigated by various electrochemical techniques such as open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of these investigations showed enhancement in inhibition efficiencies with the increasing of inhibitor concentration. The protective film formed on carbon steel surface was analyzed using an energy dispersive X-ray analysis (EDX) technique. Also, scanning electron microscope (SEM) was used to study the surface morphology of steel surface in the absence and presence of 400 ppm of the additive. (C) 2010 Elsevier B.V. All rights reserved.