The papaya leaves were extracted via ultra-pure water. The obtained papaya leaves extract (PLE) was used as the eco-friendly inhibitor for Cu in the H2SO4 corrosion medium. The experimental results showed that PLE was a mixed-type inhibitor and exhibited excellent anti-corrosion nature over a certain temperature range. Morphological analysis test results at different temperatures strongly proved the anti-corrosion nature of PLE. The XPS test results found that an adsorption film of Cu-S bond and Cu-N bond was formed on the Cu surface. This barrier film conformed to Langmuir mono-layer adsorption. Corrosion kinetics and thermodynamic parameters were calculated and discussed. (C) 2020 Elsevier Inc. All rights reserved.