The inhibition effect of some amino acids towards the corrosion of aluminum in I M HCl + 1 M H2SO4 solution was investigated using weight loss measurement, linear polarization and SEM techniques. The results drawn from the different techniques are comparable. The used amino acids were alanine, leucine, valine, proline, methionine, and tryptophan. The effect of inhibitor concentration and temperature against inhibitor action was investigated. It was found that these amino acids act as good inhibitors for the corrosion of aluminum in 1 M HCl + I M H2SO4 solution. Increasing inhibitor concentration increases the inhibition efficiency and with increasing temperature the inhibition efficiency decreases. It was found that adsorption of used amino acids on aluminum surface follows Langmuir and Frumkin isotherms. (c) 2004 Elsevier B.V. All rights reserved.