X-ray photoelectron spectra of 4,4′-bis(4 styryl-styryl) benzene oligomer (4PV) films metallized with chromium and aluminum films were used to investigate the nature of 4PV–metal interfacial reactions. The changes in the core level spectra of carbon, metal, and oxygen indicated the formation of a carbide in a chromium covered oligomer and a metal–oxide carbon and/or carbide in aluminum covered films. Yet no apparent reaction was observed in the interfacial layer when depositing the oligomer film on the chromium layer. These reactions are used as a possible explanation for the electrical characteristics of diodes made from these materials. ©1997 American Institute of Physics.