Synchrotron-based x-ray diffuse scattering (XDS) for the in situ study of electrochemically induced pitting on metal surfaces is demonstrated for the first time. We show how the intensity distribution of the x-rays scattered in the off-specular direction from a copper electrode in 0.01M NaHCO3 solution can give information on the development of pits on the copper surface as a function of time. The pits were found to be quasi-randomly distributed with a short range correlation. Average size, pit depth, and distance between pits were obtained.