The corrosion behavior of AZ91D magnesium alloy in alkaline chloride solution was investigated by electrochemical noise (EN). The wavelet transform, as well as noise resistance (R-n) and power spectral density (PSD), had been employed to analyze the EN data. It was revealed that there exist three different stages of corrosion for AZ91D magnesium alloy in alkaline chloride solution, including an anodic dissolution process companying with the growth, absorption and desorption of hydrogen bubbles, a development of pitting corrosion, an inhibition process by protective MgH2 film. The results demonstrated that energy distribution plot (EDP) was a powerful tool to provide useful information about the dominant process for the different corrosion stages. (c) 2007 Published by Elsevier Ltd.