A method has been developed for analyzing XPS depth profiles to quantify the segregation of alloying elements in passive systems, for determining the relative extents of selective dissolution and selective oxidation of the alloying elements, and for understanding the mechanisms involved. A sputter kinetic model is proposed to correct depth profiles when preferential sputtering occurs. Analysis of XPS depth profiles for a passivated Ni-W (5.86%) alloy has been performed to illustrate the method.