The purpose of this paper is to study the inhibition effect of xylenol orange on the corrosion of Aluminum (2S Grade) in 0.4 -0.6 M HCl over the temperature range of 40-60°C. It also aims to make an attempt to correlate both thermodynamic parameters and kinetic parameters with the inhibition effect. The inhibition efficiencies of xylenol orange are investigated by weight loss and potentiodynamic polarization methods. The corrosion rate of aluminum decreased with increasing inhibitor concentrations and the efficiency of inhibition increased with increasing concentration of inhibitor up to almost 87% in 0.4M HCL and up to 84% in 0.6M HCL. The concentrations of inhibitor were in the range of 2 mM to 8mM. Xylenol orange acts as a good inhibitor and inhibition efficiency increases with the inhibitor concentration while it decreases with HCl concentration and temperature. The adsorption of inhibitor on the Aluminum surface obeys the Langmuir adsorption isotherm equation. The inhibition effect is satisfactorily explained by both thermodynamic and kinetic parameters. The experimental data have been treated with adsorption theory and kinetic equations successfully. Polarization curves show that xylenol orange is a mixed-type inhibitor in hydrochloric acid. Key words: Corrosion Aluminum Hydrochloric acid xylenol orange Inhibitor.