The subject of this work involves the investigation of the polarization behaviour of aluminium as well as of three of aluminium - base alloys in sodium hydroxide solutions over temperature range (298 - 313 K). The major subjects of the work and the main results obtained may be presented as follows : 1- Polarization behaviour studies of pure Al and its three alloys Al-Cu-Mg (2024), Al-Mg (5083), and Al-Zn-Mg (7075). The research was performed in three concentration of NaOH solution at pH values of 13, 11, and 9. The polarization behaviour of pure Al and its alloys have been examined using a potentiostat (Corroscript) which was obtained from Tacussel (France) at a scan rate of 0.3 Volt per minute. The main results obtained were expressed in terms of the corrosion potentials (Ecorr) and corrosion current densities (icorr). Cathodic and anodic Tafel slopes and transfer coefficients were calculated and the results were interpreted according to the rate - determining step from charge transfer process to either chemical - desorption or to electrochemical desorption.2- Study the effect of chloride ions, the corrosion potentials and corrosion current densities also were changed considera