An x-ray projection microscope equipped with a digital camera allows a rapid and independent mapping of copper and iron ions in an aqueous sulphate solution during the corrosion/deposition process of a metallic iron electrode in a copper sulphate solution. The concentration distributions of the two species can be quantified from a pair of x-ray images acquired in 20 s with a resolution on the order of10 &mgr;m. Four pairs of images have been acquired each minute of the corrosion deposition process. This technique makes it possible to follow the concentration distribution of the two species as a function of the space(x,y)and time coordinates with a detection limit in the 10 ppm range. ©1997 American Institute of Physics.