The aim of present work was to study corrosion properties of magnetron sputtered Mg–Al alloys and characterize semiconductor properties of the surface layers developed during corrosion. Atomic force microscopy (AFM) demonstrated that sputtered alloys had a smaller grain size and a smoother surface. Corrosion and electrochemical behaviour of the alloys was studied in 0,1M (NH4)3BO3 + 0,1M NaCl (pH = 8,4) solution. Sputtered films of Al-Mg and Al had a superior resistance to pitting corrosion when compared to cast counterparts. The corrosion resistance of sputtered samples increased with decrease in Mg content. The Mott – Schottky plots of Al-Mg and pure Al electrodes showed a linear relationship between modified capacitance (C-2) on applied potential. It was concluded n – type semiconductivity for the layers on Al and p – type for Al-Mg alloys.