A green compound, N,N′-bis(2,4,6-trihydroxybenzaldehyde)-2,2-dimethylpropandiimine, was studied as an acid corrosion inhibitor for X80 steel. Aqueous 15% HCl was utilized for simulating the oil well acidizing fluid at various temperatures. The inhibition performance was assessed using the weight loss method, the electrochemical impedance, the polarization, and the scanning electron microscopy. Polarization investigations showed that the studied diimine inhibitor delays both the cathodic and anodic reactions over chemical adsorption and blocks the active corrosion sites. The adsorption procedure was performed physically as best estimated using the Langmuir adsorption isotherm. It was observed that, the adsorption process was spontaneous and exothermic in the direction of a rise in the bulk phase entropy. The efficiency of the inhibitor was reduced by increasing temperature and raised with an increasing amount of the inhibitor. Impedance data indicated that as the inhibitor amount enhanced the charge transfer resistance of steel also increased while the double layer capacitance decreased. Kinetic and thermodynamic factors such as the activation energy, enthalpy, entropy and the Gibbs free energy of activation and adsorption were computed. Scanning electron microscopy was utilized to examine the steel surface in the presence or the absence of the inhibitor, showing excellent surface protection by the studied inhibitor.