Methyl cellulose was tested as inhibitor for corrosion of aluminum and aluminum silicon alloys in 0.1M NaOH solution. The inhibition action of methyl cellulose was studied using potentiostatic polarization, electrochemical impedance spectroscopy (EIS), cyclic voltammetry and potentiodynamic anodic polarization techniques. Effect of temperature on the inhibition efficiency of studied and the values of activation thermodynamic parameters were calculated and explained. The inhibition efficiency increases with increasing the concentration of methyl cellulose and decreases with increasing temperature as well as Si content. This was attributed to a lower affinity of the inhibitor to adsorb on Si than on Al. The inhibition action was explained on the basis of adsorption of methyl cellulose on the surface of Al or Al-Si alloys forming a barrier of mass and charge transfer leading to protect the metal surface from the aggressive ions