Aluminum corrosion rate was studied in the absence and presence of some tertiary ketonic Mannich bases in 2M HCl solution, using weight loss and galvanostatic polarization techniques. The two methods gave similar results. The results showed that the inhibitor efficiency increases with increasing inhibitor concentration and decreases with increasing the temperature of the system. The adsorption of these Mannich bases on Al surface is found to obey Temkin's adsorption isotherm. Galvanostatic polarization studies showed that these compounds are mixed-type inhibitors. Some thermodynamic parameters were computed and discussed. Finally, the influence of the chemical structure of the tertiary ketonic Mannich bases on their inhibition efficiencies is discussed.