In this employ, we deliberate the effectuality of corroding inhibition of carbon steel API 5 L Gr – B in HCl 1M solution using the n-butanolic extract taken of Inula Viscosa plant. The repressive strength was observed by the electrochemical methods, Videlicet potentiodynamic condition and impedance measurements. The results indicated that the forbiddance efficiency increases with exploding choose attention. A maximum inhibition rate of 92.37 % was recorded at 600 ppm of inhibitor denseness according to the potentiodynamic measurements. The extract seems to be a goodness corroding inhibitor of electrode writing based on the obtained results. The adsorption on the element articulator was instituted to obey to Langmuir isotherm. In expansion, the HOMO and LUMO analyzing were carried out utilizing the useful thickness hypothesis strategy (DFT / B3LYP). Since HOMO and LUMO are the foremost critical orbitals in atoms, they are exceptionally valuable for understanding certain atomic properties. In expansion, from the outcome of the DFT calculations, we obtained as follows: the total dipole moment of the molecule (μ), the absolute hardness (η), the absolute electronic negativity (χ).