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Nitrogen-containing heterocyclic organic compounds have been found to be effective in corrosion inhibitors, especially in hydrochloric acid media. The purpose of this study is to investigate the inhibition performance of N¹, N¹, N⁵, N⁵-tetrakis ((1H-pyrazol-1-yl) methyl) naphthalene-1, 5-diamine (NPD) on mild steel in 1 M HCl solution. The inhibitive action of this compound against the corrosion of mild steel in 1 M HCl solution has been investigated using weight loss measurements, Tafel Polarization and electrochemical impedance spectroscopy (EIS) techniques. The results obtained from the different corrosion evaluation techniques are in good agreement. Results obtained reveal that this compound performs excellently as corrosion inhibitor for mild steel in HCl 1M solution. The temperature effect on the corrosion behavior of mild steel in 1 M HCl with and without product at different concentrations was studied in the temperature range from 313 to 343 K. The adsorption free energy and activation parameters for the mild steel dissolution reaction were determined. Adsorption of this inhibitor on the mild steel surface in 1M HCl follows the Langmuir isotherm model. The surface characteristics of inhibited and uninhibited mild steel were investigated by scanning electron microscopy (SEM) and EDX studies. Quantum chemical approach, using the density functional theory (DFT)at B3LYP/6-31G (d,p) level, was realized in order to explain the inhibitory action and to get a better understanding about the relationship between the inhibition efficiency and molecular structure of NPD and the calculated quantum chemical parameters were discussed. The theoretical results were found to be consistent with the experimental data.