A miscible blend of poly(methyl methacrylate) and poly(styrene-co-acrylonitrile) and an immiscible blend of poly(methyl methacrylate) and polyacrylonitrile were metallized by nickel, and their surfaces were analyzed by X-ray photoelectron spectroscopy. Before metallization, the heteroatom distribution at the polymer surface was very different in the miscible and immiscible blends. However, this distribution was modified during metallization, which was only possible via polymer-bond breaking, leading to similar compositions at the two interfaces. Oxygen exhibited a better affinity with nickel than nitrogen, but nickel oxide and nickel nitride were both formed at the interface. Nickel nitride prevented the metal from diffusing into the substrate, playing the role of a barrier, thus driving the oxygen to the metal layer. Amorphous carbon was also detected at the interface as a new carbon species, but it did not have any significant influence on the changes induced in the distribution of heteroatoms at the polymer surfaces. (C) 2004 Wiley Periodicals, Inc.