en Research Paper Research Paper The inhibition behavior of N,N′-bis(2,4,6-trihydroxyacetophenone)-propandiimine (THAPP) as an environmentally friendly Salen Ligand on the corrosion inhibition of mild steel was studied in alkaline solution (pH=10) containing 3% NaCl. Measurements were carried out using electrochemical and surface techniques. The experimental results suggested that this compound was an effective corrosion inhibitor for mild steel and the protection efficiency was increased with the increase in inhibitor concentration. Polarization curves indicated that this organic compound was a mixed-type inhibitor. Adsorption on the mild steel surface follows the Langmuir isotherm model. Activation parameters and thermodynamic adsorption parameters of the corrosion process such as E a , ΔH, ΔS, K ads , and ΔG ads were calculated by the obtained corrosion currents at different temperatures Corrosion, Inhibitor, adsorption isotherm, Langmuir. 34 46 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-127-84&slc_lang=en&sid=1 J. Dahdele 180031947532846003175 180031947532846003175 No Abadan Faculty of Petroleum Engineering, Petroleum University of Technology, Abadan, Iran. I. Danaee danaee@put.ac.ir 180031947532846003176 180031947532846003176 Yes Abadan Faculty of Petroleum Engineering, Petroleum University of Technology, Abadan, Iran. G. H. Rashed 180031947532846003177 180031947532846003177 No Abadan Faculty of Petroleum Engineering, Petroleum University of Technology, Abadan, Iran. M. Rashvandavei 180031947532846003178 180031947532846003178 No Department of Chemistry, K. N. Toosi University of Technology, Tehran, Iran.