Passive behavior of AA6061 Al alloy in borate buffer solutions of various pH values ranging from 8.25 to 6.57 have been studied by using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization curves showed that AA6061 Al alloy show excellent passive behavior in borate buffer solutions of various pH values ranging from 8.25 to 6.57. EIS results showed that the changes in the pH lead to one distinct behavior in the EIS plots. Moreover, it can be concluded that the passive film formed on AA6061 Al alloy shows its best protective behavior when pH interval is 6.81, and if the pH is higher or lower than this interval the protective properties of passive film will decrease.