The inhibition efficiencies of two new synthesized Schiff bases have been investigated for aluminium in 0.5?M HCl solution using experimental and theoretical methods. Potentiodynamic polarization and EIS method were used to determine the inhibition efficiencies. From the experimental results it has been found that both compounds adsorb on the aluminium surface according to the Temkin adsorption isotherm. Quantum chemical calculations were further applied to reveal the adsorption structure and explain the experimental results. A good correlation between the quantum chemical parameters and the experimental inhibition efficiency has been found.