During corrosion, currents passing from anodes to cathodes generate magnetic fields. Fitting corrosion of aluminium alloys in aggressive media was detected through magnetic field measurements, without electrical connection to the sample and without reference or auxiliary electrodes in the corrosion cell. A sodium chloride solution containing hydrogen peroxide or a solution of potassium hydroxide 2 mol l(-1) solution was used for corrosion tests. Two magnetometers developed by LETI were used: a superconducting quantum interference device (SQUID) magnetometer and a nuclear magnetic resonance (NMR) magnetometer. The SQUID provided information on spatial distribution and direction of the currents. The NMR magnetometer was better for studying the development of the corrosion over time.