The galvanic corrosion behavior of a high alloy CrMnNi cast steel and the magnesium alloy AZ31 was analyzed by potentiodynamic polarization, electrochemical noise and acoustic emission in a 10-3 M sodium chloride solution. From the polarization curves the characteristics of the steel/electrolyte/magnesium system were extracted and used for the evaluation of galvanic effects. Subsequently, the electrochemical noise (EN) and the acoustic emission (AE) behavior were analyzed simultaneously for determination of the corrosion sensitivity of the magnesium alloy. The noise signal was analyzed by continuous wavelet transform and correlated to the AE result. The characteristics of the AE signal indicated the initiation of pitting corrosion at the magnesium electrode. Additionally, the subsequent electron microscopic observations exhibit no significant damage evolution at the steel surface, whereas the magnesium alloy revealed a pitting and filiform-like corrosion attack.